The recent attempts by the People's Republic of China to smoothen relations with both South and North Korea remind us how complex and problematic these ties have been during the modern era.
The relationship between the peninsula and the mainland, in fact, extends back nearly two millennia, to an era when the modern notions of "China" and especially "Korea" did not necessarily apply.
Since then, Korea's relationship with China has been one of "love-hate," oscillating from close alliance and peaceful cultural exchange to confrontation and bitter rivalry. Indeed, that Korea is still in existence is somewhat of a miracle, given the pressures that eventually extinguished the independent standing of most other smaller civilizations on China's periphery.
But this survival, so central to Koreans' sense of national identity, also depended at times on Chinese assistance. This again reinforces the challenges of passing judgment on China's historical impact on the peninsula.
Without China, there might not have been a need for early polities on the peninsula to cohere into a single state. Korea itself arose, and continually developed thereafter, in opposition to China, or a quest to distinguish the peninsula's people and governing order from that of the Middle Kingdom, as much as in emulation.
Without question, since earliest times Korea's elites and rulers drew inspiration, models, and other cultural features from China, the fount of high civilization. But Chinese attempts to conquer or absorb the peoples of the peninsula generated a fierce resistance that constituted the birth of what came to be Korea itself.
This happened twice in the seventh century, which can be considered the originating era of Korea as a nation state, or at least as a distinctive people and coherent polity. Goguryeo, which began centuries earlier on territory that encompassed today's Manchuria and northern Korea, had to fend off waves of Chinese attempts to pacify and conquer it.
The largest such campaign took place, it appears, in 612, by the Sui Dynasty. Goguryeo successfully beat back the Chinese that time, but it had to endure several more such attacks, and finally it succumbed not to China but rather to an alliance between China and a peninsular rival, Silla.
In the mid-seventh century Silla finally brought resolution to centuries of confrontation between the peninsular states. It did so by turning to China, ruled by the Tang Dynasty, for assistance in defeating first the kingdom of Baekje, on the southwestern part of the peninsula, and then Goguryeo. Almost immediately thereafter, however, Silla had to repel an effort by its erstwhile ally, the Tang, to absorb the entire peninsula.
Thereafter the dominant, though by no means exclusive, form of the Chinese-Korean relationship became settled: a tributary alliance in which the Korean state gained protection from its massive neighbor in exchange for ritual and material "tributes" or gifts that signaled a subordinate but still independent position.
This worked in preventing the Chinese from taking further military action, but it did not always work in stopping other peoples who wanted to rule China from threatening and invading Korea. During the Goryeo era (935-1392), which succeeded Silla, groups originating in Manchuria and central Asia, such as the Khitan and Jurchen, penetrated Korea's northern frontier. And finally the Mongols, on their way to conquering much of Eurasia, succeeded in subduing Korea.
For nearly a century Mongol-controlled China treated Goryeo somewhat like a colony, directly controlling its northern territories and constantly interfering in Goryeo's internal affairs; in fact the Mongol emperor in Beijing even determined Goryeo's monarch, whose ancestry, beginning with his mother, was usually more Mongol than Korean.
The traditional relationship between China and Korea was restored in the second half of the 14th century following the overthrow of the Mongols by the Ming Dynasty in China and the establishment of the Joseon Kingdom in Korea. And further strengthened was China's role as the source of high civilization, as Joseon's founding fathers deemed a comprehensive form of Confucianism as Korea's state ideology, which included a formal reverence for China's superior diplomatic standing.
This came in handy when Japan invaded Korea in the late 16th century. Without the Ming army's early and forceful intervention, Korea likely would have fallen, perhaps permanently, into status as Japanese territory. Of course Chinese motives were not purely altruistic: They could not tolerate a hostile Japan on its borders.
Such a realpolitik, practical view in fact has always driven the China-Korea relationship, and China's last major intervention on the peninsula, too, should be remembered along these lines. When the new Chinese communist state aided the North Koreans in the Korean War in 1950, it did so out of its own interests, first and foremost. And it paid dearly, in the form of tens of thousands of Chinese soldiers killed in the fighting against the U.N. forces.
Since then, the communist alliance between mainland China and North Korea (and eventually the relations between China and South Korea as well) has reflected the friendly as well as not-so-friendly ties that have marked the relationship since ancient times.
Without Chinese support, North Korea would not have survived the Korean War and likely would not have survived the collapse of the Soviet Union in the early 1990s. Yet in their official historical narrative, the North Koreans have denied this indispensable Chinese aid, adding another twist to China's multifaceted, complex role in the Korean past.
Kyung Moon Hwang is associate professor in the Department of History, University of Southern California. He is the author of "A History of Korea ― An Episodic Narrative" (Palgrave Macmillan, 2010). The Korean translation was published as 황경문, "맥락으로 읽는 새로운 한국사" (21세기 북스, 2011).