Immigration, affirmative action, multilingualism, ethnic diversity--my state of California pioneered these controversial policies, and it is now pioneering a backlash against them. A glance into the classrooms of the Los Angeles public schools, where my sons are being educated, fleshes out the abstract debates with the faces of children. Those pupils speak more than 80 languages in their homes; English-speaking whites are in the minority. Every single one of my sons’ playmates has at least one parent or grandparent who was born outside the United States. That’s true of my sons also--three of their four grandparents were immigrants to this country. But the diversity that results from such immigration isn’t new to America. In fact, immigration is simply restoring the diversity that existed here for thousands of years and that diminished only recently; the area that now makes up the mainland United States, once home to hundreds of Native American tribes and languages, did not come under the control of a single government until the late nineteenth century.

In these respects, ours is a thoroughly normal country. Like the United States, all but one of the world’s six most populous nations are melting pots that achieved political unification recently and that still support hundreds of languages and ethnic groups. Russia, for example, once a small Slavic state centered on Moscow, did not even begin its expansion beyond the Ural Mountains until 1582. From then until the late nineteenth century, Russia swallowed up dozens of non-Slavic peoples, many of whom, like the people of Chechnya today, retain their original language and cultural identity. India, Indonesia, and Brazil are also recent political creations (or re-creations, in the case of India) and are home to about 850, 703, and 209 languages, respectively.

The great exception to this rule of the recent melting pot is the world’s most populous nation, China. Today China appears politically, culturally, and linguistically monolithic. (For the purposes of this article, I exclude the linguistically and culturally distinct Tibet, which was also politically separate until recently.) China was already unified politically in 221 B.C. and has remained so for most of the centuries since then. From the beginnings of literacy in China over 3,000 years ago, it has had only a single writing system, unlike the dozens in use in modern Europe. Of China’s billion-plus people, over 700 million speak Mandarin, the language with by far the largest number of native speakers in the world. Some 250 million other Chinese speak seven languages as similar to Mandarin and to each other as Spanish is to Italian. Thus, while modern American history is the story of how our continent’s expanse became American, and Russia’s history is the story of how Russia became Russian, China’s history appears to be entirely different. It seems absurd to ask how China became Chinese. China has been Chinese almost from the beginning of its recorded history.

We take this unity of China so much for granted that we forget how astonishing it is. Certainly we should not have expected such unity on the basis of genetics. While a coarse racial classification of world peoples lumps all Chinese people together as Mongoloids, that category conceals much more variation than is found among such (equally ill-termed) Caucasian peoples as Swedes, Italians, and Irish. Northern and southern Chinese, in particular, are genetically and physically rather different from each other: northerners are most similar to Tibetans and Nepali, southerners to Vietnamese and Filipinos. My northern and southern Chinese friends can often distinguish each other at a glance: northerners tend to be taller, heavier, paler, with more pointed noses and smaller eyes.

The existence of such differences is hardly surprising: northern and southern China differ in environment and climate, with the north drier and colder. That such genetic differences arose between the peoples of these two regions simply implies a long history of their moderate isolation from each other. But if such isolation existed, then how did these peoples end up with such similar languages and cultures?

China’s linguistic near-unity is also puzzling in comparison with the linguistic disunity of other parts of the world. For instance, New Guinea, although it was first settled by humans only about 40,000 years ago, evolved roughly 1,000 languages. Western Europe has by now about 40 native languages acquired just in the past 6,000 to 8,000 years, including languages as different as English, Finnish, and Russian. Yet New Guinea’s peoples are spread over an area less than one-tenth that of China’s. And fossils attest to human presence in China for hundreds of thousands of years. By rights, tens of thousands of distinct languages should have arisen in China’s large area over that long time span; what has happened to them? China too must once have been a melting pot of diversity, as all other populous nations still are. It differs from them only in having been unified much earlier: in that huge pot, the melting happened long ago.

A glance at a linguistic map is an eye-opener to all of us accustomed to thinking of China as monolithic. In addition to its eight big languages--Mandarin and its seven close relatives (often referred to collectively as Chinese), with between 11 million and 700 million speakers each--China also has some 160 smaller languages, many of them with just a few thousand speakers. All these languages fall into four families, which differ greatly in their distributions.

At one extreme, Mandarin and its relatives, which constitute the Chinese subfamily of the Sino-Tibetan language family, are distributed continuously from the top of the country to the bottom. One distinctive feature of all Sino-Tibetan languages is that most words consist of a single syllable, like English it or book; long, polysyllabic words are unthinkable. One could walk through China, from Manchuria in the north to the Gulf of Tonkin in the south, without ever stepping off land occupied by native speakers of Chinese.

The other three families have broken distributions, being spoken by islands of people surrounded by a sea of speakers of Chinese and other languages. The 6 million speakers of the Miao-Yao family are divided among five languages, bearing colorful names derived from the characteristic colors of the speakers’ clothing: Red Miao, White Miao (alias Striped Miao), Black Miao, Green Miao (alias Blue Miao), and Yao. Miao-Yao speakers live in dozens of small enclaves scattered over half a million square miles from southern China to Thailand.

The 60 million speakers of languages in the Austroasiatic family, such as Vietnamese and Cambodian, are also scattered across the map, from Vietnam in the east to the Malay Peninsula in the south to northeastern India in the west. Austroasiatic languages are characterized by an enormous proliferation of vowels, which can be nasal or nonnasal, long or extrashort, creaky, breathy, or normal, produced with the tongue high, medium high, medium low, or low, and with the front, center, or back of the tongue. All these choices combine to yield up to 41 distinctive vowel sounds per language, in contrast to the mere dozen or so of English.

The 50 million speakers of China’s fourth language family, Tai- Kadai, are scattered from southern China southward into peninsular Thailand and west to Myanmar (Burma). In Tai-Kadai languages, as in most Sino- Tibetan languages, a single word may have different meanings depending on its tone, or pitch. For example, in Thai itself the syllable maa means horse when pronounced at a high pitch, come at a medium pitch, and dog at a rising pitch.

Seen on a map, the current fragmented distribution of these language groups suggests a series of ancient helicopter flights that dropped speakers here and there over the Asian landscape. But of course nothing like that could have happened, and the actual process was subtractive rather than additive. Speakers of the now dominant language expanded their territory and displaced original residents or induced them to abandon their native tongues. The ancestors of modern speakers of Thai and Laotian, and possibly Cambodian and Burmese as well, all moved south from southern China and adjacent areas to their present locations within historical times, successively inundating the settled descendants of previous migrations. Chinese speakers were especially vigorous in replacing and linguistically converting other ethnic groups, whom they looked down on as primitive and inferior. The recorded history of China’s Chou Dynasty, from 1111 B.C. to 256 B.C., describes the conquest and absorption of most of China’s non-Chinese-speaking population by Chinese-speaking states.

Before those relatively recent migrations, who spoke what where? To reconstruct the linguistic map of the East Asia of several thousand years ago, we can reverse the historically known linguistic expansions of recent millennia. We can also look for large, continuous areas currently occupied by a single language or related language group; these areas testify to a geographic expansion of that group so recent that there has not been enough time for it to differentiate into many languages. Finally, we can reason conversely that modern areas with a high diversity of languages within a given language family lie closer to the early center of distribution of that language family. Using those three types of reasoning to turn back the linguistic clock, we conclude that speakers of Chinese and other Sino-Tibetan languages originally occupied northern China. The southern parts of the country were variously inhabited by speakers of Miao- Yao, Austroasiatic, and Tai-Kadai languages--until they were largely replaced by their Sino-Tibetan-speaking neighbors.

An even more drastic linguistic upheaval appears to have swept over tropical Southeast Asia to the south of China, in Thailand, Myanmar, Laos, Cambodia, Vietnam, and peninsular Malaysia. It’s likely that whatever languages were originally spoken there have now become extinct--most of the modern languages of those countries appear to be recent invaders, mainly from southern China. We might also guess that if Miao-Yao languages could be so nearly overwhelmed, there must have been still other language families in southern China that left no modern descendants whatsoever. As we shall see, the Austronesian family (to which all Philippine and Polynesian languages belong) was probably once spoken on the Chinese mainland. We know about it only because it spread to Pacific islands and survived there.

The language replacements in East Asia are reminiscent of the way European languages, especially English and Spanish, spread into the New World. English, of course, came to replace the hundreds of Native American languages not because it sounded musical to indigenous ears but because English-speaking invaders killed most Native Americans by war, murder, and disease and then pressured the survivors into adopting the new majority language. The immediate cause of the Europeans’ success was their relative technological superiority. That superiority, however, was ultimately the result of a geographic accident that allowed agriculture and herding to develop in Eurasia 10,000 years earlier. The consequent explosion in population allowed the Europeans to develop complex technologies and social organization, giving their descendants great political and technological advantages over the people they conquered. Essentially the same processes account for why English replaced aboriginal Australian languages and why Bantu languages replaced subequatorial Africa’s original Pygmy and Khoisan languages.

East Asia’s linguistic upheavals thus hint that some Asians enjoyed similar advantages over other Asians. But to flesh out the details of that story, we must turn from linguistics to archeology.

As everywhere else in the world, the eastern Asian archeological record for most of human history reveals only the debris of hunter- gatherers using unpolished stone tools. The first eastern Asian evidence for something different comes from China, where crop remains, bones of domestic animals, pottery, and polished stone tools appear by around 7500 B.C. That’s no more than a thousand years after the beginnings of agriculture in the Fertile Crescent, the area with the oldest established food production in the world.

In China plant and animal domestication may even have started independently in two or more places. Besides differences in climate between north and south, there are also ecological differences between the interior uplands (which are characterized by mountains like our Appalachians) and the coastal lowlands (which are flat and threaded with rivers, like the Carolinas). Incipient farmers in each area would have had different wild plants and animals to draw on. In fact, the earliest identified crops were two drought-resistant species of millet in northern China, but rice in the south.

The same sites that provided us with the earliest evidence of crops also contained bones of domestic pigs, dogs, and chickens--a livestock trinity that later spread as far as Polynesia. These animals and crops were gradually joined by China’s many other domesticates. Among the animals were water buffalo (the most important, since they were used for pulling plows), as well as silkworms, ducks, and geese. Familiar later Chinese crops include soybeans, hemp, tea, apricots, pears, peaches, and citrus fruits. Many of these domesticated animals and crops spread westward in ancient times from China to the Fertile Crescent and Europe; at the same time, Fertile Crescent domesticates spread eastward to China. Especially significant western contributions to ancient China’s economy were wheat and barley, cows and horses, and to a lesser extent, sheep and goats.

As elsewhere in the world, food production in China gradually led to the other hallmarks of civilization. A superb Chinese tradition of bronze metallurgy arose around 3000 B.C., allowing China to develop by far the earliest cast iron production in the world by 500 B.C. The following 1,500 years saw the outpouring of a long list of Chinese inventions: canal lock gates, deep drilling, efficient animal harnesses, gunpowder, kites, magnetic compasses, paper, porcelain, printing, sternpost rudders, and wheelbarrows, to name just a few.

China’s size and ecological diversity initially spawned many separate local cultures. In the fourth millennium B.C. those local cultures expanded geographically and began to interact, compete with each other, and coalesce. Fortified towns appeared in China in the third millennium B.C., with cemeteries containing luxuriously decorated graves juxtaposed with simpler ones--a clear sign of emerging class differences. China became home to stratified societies with rulers who could mobilize a large labor force of commoners, as we can infer from the remains of huge urban defensive walls, palaces, and the Grand Canal--the longest canal in the world-- linking northern and southern China. Writing unmistakably ancestral to that of modern China is preserved from the second millennium B.C., though it probably arose earlier. The first of China’s dynasties, the Hsia Dynasty, arose around 2000 B.C. Thereafter, our archeological knowledge of China’s emerging cities and states becomes supplemented by written accounts.

Along with rice cultivation and writing, a distinctively Chinese method for reading the future also begins to appear persistently in the archeological record, and it too attests to China’s cultural coalescence. In place of crystal balls and Delphic oracles, China turned to scapulimancy--burning the scapula (shoulder bone) or other large bone of an animal, such as a cow, then prophesying from the pattern of cracks in the burned bone. From the earliest known appearance of oracle bones in northern China, archeologists have traced scapulimancy’s spread throughout China’s cultural sphere.

Just as exchanges of domesticates between ecologically diverse regions enriched Chinese food production, exchanges between culturally diverse regions enriched Chinese culture and technology, and fierce competition between warring chiefdoms drove the formation of ever larger and more centralized states. China’s long west-east rivers (the Yellow River in the north, the Yangtze in the south) allowed crops and technology to spread quickly between inland and coast, while their diffusion north and south was made easy by the broad, relatively gentle terrain north of the Yangtze, which eventually permitted the two river systems to be joined by canals. All those geographic factors contributed to the early cultural and political unification of China. In contrast, western Europe, with an area comparable to China’s but fragmented by mountains such as the Alps, and with a highly indented coastline and no such rivers, has never been unified politically.

Some developments spread from south to north in China, especially iron smelting and rice cultivation. But the predominant direction of spread seems to have been the other way. From northern China came bronze technology, Sino-Tibetan languages, and state formation. The country’s first three dynasties (the Hsia, Shang, and Chou) all arose in the north in the second millennium B.C. The northern dominance is clearest, however, for writing. Unlike western Eurasia, with its plethora of early methods for recording language, including Sumerian cuneiform, Egyptian hieroglyphics, Hittite, Minoan, and the Semitic alphabet, China developed just one writing system. It arose in the north, preempted or replaced any other nascent system, and evolved into the writing used today.

Preserved documents show that already in the first millennium B.C. ethnic Chinese tended to feel culturally superior to non-Chinese barbarians, and northern Chinese considered even southern Chinese barbarians. For example, a late Chou Dynasty writer described China’s other peoples as follows: The people of those five regions--the Middle states and the Jung, Yi, and other wild tribes around them--had all their several natures, which they could not be made to alter. The tribes on the east were called Yi. They had their hair unbound, and tattooed their bodies. Some of them ate their food without its being cooked by fire. The author went on to describe wild tribes to the south, west, and north indulging in equally barbaric practices, such as turning their feet inward, tattooing their foreheads, wearing skins, living in caves, not eating cereals, and, again, eating their food raw.

States modeled on the Chou Dynasty were organized in southern China during the first millennium B.C., culminating in China’s political unification under the Chin Dynasty in 221 B.C. China’s cultural unification accelerated during that same period, as literate civilized Chinese states absorbed or were copied by the preliterate barbarians. Some of that cultural unification was ferocious: for instance, the first Chin emperor condemned all previously written historical books as worthless and ordered them burned, much to the detriment of our understanding of early Chinese history. That and other draconian measures must have helped spread northern China’s Sino-Tibetan languages over most of China.

Chinese innovations contributed heavily to developments in neighboring regions as well. For instance, until roughly 4000 B.C. most of tropical Southeast Asia was still occupied by hunter-gatherers making pebble and flake stone tools. Thereafter, Chinese-derived crops, polished stone tools, village living, and pottery spread into the area, probably accompanied by southern Chinese language families. The southward expansions from southern China of Laotians, Thai, and Vietnamese, and probably Burmese and Cambodians also, completed the Sinification of tropical Southeast Asia. All those modern peoples appear to be recent offshoots of their southern Chinese cousins.

So overwhelming was this Chinese steamroller that the former peoples of the region have left behind few traces in the modern populations. Just three relict groups of hunter-gatherers--the Semang Negritos of the Malay Peninsula, the Andaman Islanders, and the Veddoid Negritos of Sri Lanka--remain to give us any clue as to what those peoples were like. They suggest that tropical Southeast Asia’s former inhabitants may have had dark skin and curly hair, like modern New Guineans and unlike southern Chinese and modern tropical Southeast Asians. Those people may also be the last survivors of the source population from which New Guinea and aboriginal Australia were colonized. As to their speech, only on the remote Andaman Islands do languages unrelated to the southern Chinese language families persist--perhaps the last linguistic survivors of what may have been hundreds of now extinct aboriginal Southeast Asian languages.

While one prong of the Chinese expansion thus headed southwest into Indochina and Myanmar, another headed southeast into the Pacific Ocean. Part of the evidence suggesting this scenario comes from genetics and linguistics: the modern inhabitants of Indonesia and the Philippines are fairly homogeneous in their genes and appearance and resemble southern Chinese. Their languages are also homogeneous, almost all belonging to a closely knit family called Austronesian, possibly related to Tai-Kadai.

But just as in tropical Southeast Asia, the archeological record in the Pacific shows more direct evidence of the Chinese steamroller. Until 6,000 years ago, Indonesia and the Philippines were sparsely occupied by hunter-gatherers. Beginning in the fourth or fifth millennium B.C., pottery and stone tools of unmistakably southern Chinese origins appear on the island of Taiwan, which is in the straits between the southern Chinese coast and the Philippines. Around 3000 B.C. that same combination of technological advances spread as a wave to the Philippines, then throughout the islands of Indonesia, accompanied by gardening and by China’s livestock trinity (pigs, chickens, and dogs). Around 1600 B.C. the wave reached the islands north of New Guinea, then spread eastward through the previously uninhabited islands of Polynesia. By 500 A.D. the Polynesians, an Austronesian-speaking people of ultimately Chinese origin, had reached Easter Island, 10,000 miles from the Chinese coast. With Polynesian settlement of Hawaii and New Zealand around the same time or soon thereafter, ancient China’s occupation of the Pacific was complete.

Throughout most of Indonesia and the Philippines, the Austronesian expansion obliterated the region’s former inhabitants. Scattered bands of hunter-gatherers were no match for the tools, weapons, numbers, subsistence methods, and probably also germs carried by the invading Austronesian farmers. Only the Negrito Pygmies in the mountains of Luzon and some other Philippine islands appear to represent survivors of those former hunter-gatherers, but they too lost their original tongues and adopted Austronesian languages from their new neighbors. However, on New Guinea and adjacent islands, indigenous people had already developed agriculture and built up numbers sufficient to keep out the Austronesian invaders. Their languages, genes, and faces live on in modern New Guineans and Melanesians.

Even Korea and Japan were heavily influenced by China, although their geographic isolation from the mainland saved them from losing their languages or physical and genetic distinctness. Korea and Japan adopted rice from China in the second millennium B.C., bronze metallurgy in the first millennium B.C., and writing in the first or early second millennium A.D.

Not all cultural advances in East Asia stemmed from China, of course, nor were Koreans, Japanese, and tropical Southeast Asians noninventive barbarians who contributed nothing. The ancient Japanese developed pottery at least as early as the Chinese did, and they settled in villages subsisting on Japan’s rich seafood resources long before the arrival of agriculture. Some crops were probably domesticated initially or independently in Japan, Korea, and tropical Southeast Asia. But China’s role was still disproportionately large. Indeed, the influence of Chinese culture is still so great that Japan has no thought of discarding its Chinese-derived writing system despite its disadvantages for representing Japanese speech, while Korea is only now replacing its clumsy Chinese- derived writing with its wonderful indigenous Hangul alphabet. The persistence of Chinese writing in Japan and Korea is a vivid twentieth- century legacy of plant and animal domestication that began in China 10,000 years ago. From those achievements of East Asia’s first farmers, China became Chinese, and peoples from Thailand to Easter Island became their cousins.