TALL jars filled with rice beer await customers by the riverside in Yanji, a city in north-eastern China close to the border with North Korea. Servers in aprons fork out spicy salads from rows of red plastic bowls. Atop a nearby trestle table a butcher has laid out three skinned dogs. The early-morning market exudes the distinctive character of Yanbian, an ethnic-Korean enclave of which Yanji is the administrative heart. Youngsters chatter in Mandarin and Korean. Shop hoardings are written in both languages.

Yanbian is the biggest of two ethnic-Korean areas on China’s side of the border. But its Korean-ness has faded over the past three decades. A stallholder who gives his surname as Piao (Park in Korean) explains that his grown-up nieces and nephews have all moved to Japan or South Korea, where he thinks they can earn three times more money. He is sure that his young daughter, who is spending her summer holiday helping at the market, will eventually choose to leave, too. The way things are going, he reckons, Yanbian’s Korean community will one day disappear.

Koreans began moving into China in the second half of the 19th century. The early migrants were victims of floods and other disasters that had made northern parts of the peninsula unfit for farming. Later generations fled the Japanese occupation of Korea, which began in 1910. When the Japanese army eventually followed the refugees north—in 1932 it incorporated a large swathe of north-east China into a puppet state called Manchukuo—the colonial authorities encouraged more Koreans to move into sparsely populated areas of the new dominion.

As it turned out, Korean militias played an important role in kicking the Japanese out in 1945. Later they sided with the Chinese Communist Party in China’s civil war. After it seized power in 1949, the party recognised Korean-Chinese as an ethnic minority and gave them special rights in their enclaves of Yanbian and the county of Changbai, both in Jilin province (see map). These included permission to use Korean as an official language and promote it in schools (pictured is a propaganda poster in Yanji, written in Korean and Chinese—the words mean “patriotism”). The two prefectures are officially designated as “autonomous” (in practice they are not at all so). Yanbian covers an area bigger than the island of Taiwan. During the 1960s some Korean-Chinese moved back to communist-ruled North Korea, which for a while seemed alluring by comparison. Today Korean-Chinese are among the more prosperous of the country’s ethnic minorities. A turning-point came in 1992, when China and South Korea opened full diplomatic relations. This encouraged big South Korean firms to set up operations in China. These often preferred to recruit Korean-speaking Chinese. A paper by Choi Woogill of Sun Moon University in South Korea says that many young people from Yanbian found white-collar jobs in such businesses, often in cities such as Beijing and Shanghai, far from their hometowns. A far greater number of Korean-Chinese began heading abroad to seek their fortunes. Of around 1.8m of them, about 1m are living outside China, with as many as 700,000 in South Korea alone. Perhaps as few as half a million remain in China’s north-east, which once was home to all but a handful of them. The outflow proved an economic boon for Yanji. Money sent back by the migrants to their relatives in the city helped to make it livelier and more affluent than many other places in China’s north-east, a centre of state-owned heavy industry that in recent years has often been described as a “rustbelt”. A taxi driver belonging to China’s main ethnic group, the Han, says that there are now hardly any ethnic Koreans driving cabs. He guesses that they are no longer attracted by the possible earnings.

But while Korean-Chinese have been gaining in wealth, their enclaves have been withering culturally. The proportion of ethnic-Koreans in Yanbian has fallen from more than three-fifths in 1949 to slightly more than one-third today. The exodus has been particularly evident in the countryside, where—as often across China—farmers have been abandoning the fields in favour of better-earning work in the cities. The number of Korean-language schools has been plummeting amid a shortage of teachers and students. The departures have split families. Some 60-80% of ethnic-Korean children in Yanbian live apart from at least one parent, according to Mr Choi.

For the government, this is a mixed blessing. Officials in Yanbian want the area to maintain its Korean character, which is an attraction for tourists. But the out-migration also helps to dilute the numbers of ethnic Koreans along the border. In their book “China on the Edge”, Carla Freeman and Drew Thompson describe how, in the 2000s, some Chinese officials were wary of attracting South Korean investors to Yanbian, fearing they were treating it as Korean territory. South Korean nationalists sometimes refer to the area as the “third Korea”.

The Communist Party is mindful of claims by fringe nationalist groups in South Korea that Yanbian is Korean territory that ought one day to be reclaimed. Such people argue that border agreements signed by China in 1909 with Japanese colonialists and in 1962 with North Korea should be annulled, because they were negotiated with illegitimate governments, as the nationalists see it (see article).

No dual loyalty here

These opinions do not appear to be shared in Yanbian itself. Few Korean-Chinese residents there say there is any serious conflict between their Korean ethnicity and their loyalty to China, of which they are citizens. But the party probably worries that this view could change should Yanbian’s ethnic make-up be altered by a large influx of North Korean refugees—or if the bankrupt prison-state that lurks next door were to collapse and a unified, rich and attractive Korea were to emerge.

China’s anxieties about Korean nationalism may explain its efforts, beginning in the early 2000s, to establish the Chinese-ness of the border area by funding new research into its history. There ensued an arcane but fiery debate between Chinese and Korean experts over whether the kingdom of Goguryeo, the territory of which straddled northern Korea and north-eastern China between the first and seventh centuries, was mostly Korean or Chinese in nature. Some nationalists in South Korea accused China of using its version of history to expand its territorial claims, perhaps to justify the grabbing of territory in North Korea to act as a buffer zone should the regime there fall apart.

For the moment, however, China’s main worry on its side of the border is about the economy. Last year GDP growth in Yanbian was only 3.3%, less than half the national rate. If North Korea could resolve conflicts over its nuclear programme and become more open to foreign business, “every inch of soil” in Yanbian would “turn to gold”, says Jin Qiangyi, a Korean-Chinese academic at Yanbian University.

Should this happen, plenty of far-flung Korean-Chinese would return to the border area. But few people in Yanji are holding their breath. An ethnic Korean relaxing in a park says any real change on the peninsula might take another 30 years or more. Such a scenario worries Mr Jin. By then, he says, China’s globetrotting ethnic Koreans may have been gone too long to be tempted home at all.