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I pride myself on my hard-won sense of history. World history is probably the subject I’ve studied the most on my own, starting with Somerset Plantagenet Fry’s beautifully illustrated DK History of the World at age 15. I studied the thing obsessively for nearly a year, taking copious notes and neglecting my school history syllabus. It’s been the best intellectual investment of my life. Since then, I periodically return to history to refresh my brain whenever I think it my thinking is getting stale. Most recently, I’ve been reading Gibbon’s Decline and Fall of the Roman Empire and Alfred Thayer Mahan’s The Influence of Sea Power Upon History. My tastes have gradually shifted from straightforward histories by modern historians to analytical histories with a specific angle, preferably written by historians from eras besides our own.

The big value to studying world history is that no matter how much you know or think you know, one new fact can completely rewire your perspectives. The biggest such surprise for me was understanding the real story (or as real as history ever gets) of how iron came to displace bronze, and what truly happened in the shift between the Bronze Age and the Iron Age.

What comes to mind when you think “bronze?” Hand-crafted artifacts, right?

What about iron? Big, modern, steel mills and skyscrapers, right? Iron metallurgy is obviously the more advanced and sophisticated industry in our time.

The Iron Age displaced the Bronze Age sometime in the late second millennium BC. The way the story is usually told, iron was what powered the rise of the obscure barbarian-nomads known as the Aryans throughout the ancient world.

You could be forgiven for thinking that this was a sudden event based on iron being suddenly discovered and turning out to be a “superior” material for weaponry, and the advantage accidentally happening to fall to the barbarian-nomads rather than the civilization centers.

Far from it.

Here’s the real (or “less wrong”) story in outline.

The Clue in the Tin

You see iron and bronze co-existed for a long time. Iron is a plentiful element, and can be found in relatively pure forms in meteorites (think of meteorites as the starter kits for iron metallurgy). Visit a geological museum sometime to see for yourself (I grew up in a steel town).

It is hard to smelt and work, but basically once you figure out some rudimentary metallurgy and can generate sufficiently high temperatures to work it, you can handle iron, at least in crude, brittle and easily rusted forms. Not quite steel, but then who cares about rust and extreme hardness if the objective is to split open the skull of another guy in the next 10 seconds.

Bronze on the other hand is a very difficult material to handle. There have been two forms in antiquity. The earlier Bronze Age was dominated by what is known as arsenical bronze. That’s copper alloyed with arsenic to make it harder. That’s not very different from iron. Copper is much scarcer and less widely-distributed of course, but it does occur all over the place. And fortunately, when you do find it, copper usually has trace arsenic contamination in its natural form. So you are starting with all the raw material you need.

The later Bronze Age though, relied on a much better material: tin bronze. Now this is where the story gets interesting. Tin is an extremely rare element. It only occurs in usable concentrations in a few isolated locations worldwide.

In fact known sources during the Bronze Age were in places like England, France, the Czech Republic and the Malay peninsula. Deep in barbarian-nomad lands of the time. As far as we can tell, tin was first mined somewhere in the Czech Republic around 2500 BC, and the practice spread to places like Britain and France by about 2000.

Notice something about that list? They are very far from the major Bronze Age urban civilizations around the Nile, in the Middle East and in the Indus Valley, of 4000-2000 BC or so.

This immediately implies that there must have been a globalized long-distance trade in tin connecting the farthest corners of Europe (and possibly Malaya) with the heart of the ancient world. Not only that, you are forced to recognize that the metallurgists of the day must have had sophisticated and deliberate alloying methods, since you cannot assume, as you might be tempted to in the case of arsenical bronze, that the ancients didn’t really know what they were doing. You cannot produce tin-bronze by accident. Tin implies skills, accurate measurements, technology, guild-style education, and land and sea trade of sufficient sophistication that you can call it an “industry.”

What’s more, the use of tin also implies that the Bronze Age civilizations didn’t just sit around inside their borders, enjoying their urban lifestyles. They must have actually traded somehow with the far corners of the barbarian-nomad world that eventually conquered them. Clearly the precursors of the Aryans and other nomadic peoples of the Bronze Age (including the Celts in Europe, the ethnic Malays, and so forth) must have had a lot of active contact with the urban civilizations (naive students of history often don’t get that humans had basically dispersed through the entire known world by 10,000 BC; “civilization” may have spread from a few centers, but people didn’t spread that way, they spread much earlier).

In fact, tin almost defines “civilization”: only the 3-4 centers of urban civilization of that period had the coordination capabilities necessary to arrange for the shipping of tin over land and sea, across long distances. It is well recognized that they had trade with each other, with different trade imbalances (there is clear evidence of land and sea trade among the Mesopotamian, Nile and Indus river valleys; the Yellow River portions of China were a little more disconnected at that time).

What is not as well recognized is that the evidence of commodities like tin indicates that these civilizations must have also traded extensively with the barbarian-nomad worlds in their interstices and beyond their borders in every direction. The iron-wielding barbarians were not shadowy strangers who suddenly descended on the urban centers out of the shadows. They were marginal peoples with whom the civilizations had relationships.

So tin implies the existence of sophisticated international trade. I suspect it even means that tin was the first true commodity money (commodity monies don’t just emerge based on their physical properties and value; they must provide a raison d’etre for trade over long distances).

Iron vs. Bronze

So what about iron? Since it was all over the place, we cannot trace the origins of iron smelting properly, and in a sense there is no good answer to the question “where was iron discovered?” It was in use as a peripheral metal for a long period before it displaced bronze (possibly inside the Bronze Age civilizations and the barbarian-nomad margins). As the Wikipedia article says, with reference to iron use before the Iron Age:

Meteoric iron, or iron-nickel alloy, was used by various ancient peoples thousands of years before the Iron Age. This iron, being in its native metallic state, required no smelting of ores.By the Middle Bronze Age, increasing numbers of smelted iron objects (distinguishable from meteoric iron by the lack of nickel in the product) appeared throughout Anatolia, Mesopotamia, the Indian subcontinent, the Levant, the Mediterranean, and Egypt. The earliest systematic production and use of iron implements originates in Anatolia, beginning around 2000 BCE. Recent archaeological research in the Ganges Valley, India showed early iron working by 1800 BC. However, this metal was expensive, perhaps because of the technical processes required to make steel, the most useful iron product. It is attested in both documents and in archaeological contexts as a substance used in high value items such as jewelry.

Unlike tin-bronze, which probably required a specific sequence of local inventions near the ore sources followed by diffusion, iron use could (and probably did) arise and evolve in multiple places in unrelated ways, because it didn’t depend on special ingredients. The idea that it might have been expensive enough, in the form of steel, to be jewelry, is reminiscent of the modern history of another metal: aluminum. Like iron, it is one of the most commonplace metals, and like iron, until a cheap manufacturing process was discovered, it was a noble metal. Rich people ate off aluminum ware and wore aluminum jewelry.

So you can tell a broader, speculative history: since you didn’t need complicated shipping and smelting to make a basic use of iron, its use could develop on the peripheries of civilization, among barbarian-nomads who didn’t demand the high quality that the tin-bronze markets did. Iron didn’t need the complicated industry that bronze did. What’s more, chances are, the bronze guilds were likely quite snooty about the crappy, rusty material outside of highly-refined and expensive jewelry uses.

But the margins, which didn’t have the tin trade or industry, had a good reason to pay attention to iron. I speculate that for the barbarian-nomad cultures that were far from the Bronze Age urban centers, the upgrade that iron provided over stone, even with the problems of rust and brittleness that plagued primitive iron, was enough for them to take down the old Bronze-powered civilizations, and then leisurely evolve iron to its modern form. I suspect a bronze-leapfrogging transition from stone to iron happened in many places, as with cellphones today in Africa.

(aside, I assume there is an equally sophisticated story about how bronze displaced stone; neolithic stone age cultures like the ones the Europeans encountered in America, were far from grunting cave-dwellers. They had evolved stone use to a high art).

By the time iron got both good enough and cheap enough to take on bronze as a serious contender for uses like weaponry, the incumbent Bronze Age civilizations couldn’t catch up. The pre-industrial barbarian-nomads had the upper hand.

Iron didn’t completely displace bronze in weaponry until quite late. As late as Alexander’s conquests, he still used bronze; iron technology was not yet good enough at the highest levels of quality, but the point is, it was good enough initially for the marginal markets, and for masses of barbarian soldiers.

Sound familiar?

This is classic disruption in the sense of Clayton Christensen. An initially low-quality marginal market product (iron) getting better and eventually taking down the mainstream market (bronze), at a point where the incumbents could do nothing, despite the extreme sophistication of their civlization, with its evolved tin trading routes and deliberate metallurgical practices.

Rewinding History

Understanding the history of bronze and iron better has forced me to rewind my sense of when “history” proper starts by at least 11,000 years. The story has given me a new appreciation for how sophisticated human beings have been, and for how long. I used to think that truly psychologically modern humans didn’t emerge till about 1200 AD. The story of bronze made me rewind my assessments to 4000 BC. Now, though I don’t know the details (nobody does), I think psychologically modern human culture must have started no later than 10,000 BC, the approximate period of what is called the Neolithic revolution.

Now I think the most interesting period in history is probably 10,000 BC to 4,000 BC. Even 20,000 BC to 10,000 BC is fascinating (that’s when the caves in Lascaux were painted), but let’s march backwards one millennium at a time.