The king of Koryŏ from 1351 to 1374, Wang Ki (1330–74), also known by his Mongolian name, Bayan-Temür, is easily one of the most enigmatic figures in Korean history. He is best known for capturing old Korean lands ceded to the Mongols, killing “pro-Yuan collaborators” in his court, and demolishing Mongol institutions of control in his country. But he also continuously claimed to be a loyal servant of the Mongols for most of his life. While Wang Ki emphasized his and his dynasty's peninsular heritage, he grew up as a collateral Chinggisid aristocrat, personally served the emperor for a decade, and married Mongol royalty to strengthen his pedigree.

The first historians to write about him in the fifteenth century were all officials of the new Korean dynasty with a vested interest in smearing Wang Ki and the old dynasty. In modern times, scholars have often told Wang Ki's story through the prism of the nation. Through Wang Ki's policies, many modern-day scholars of Korean history discovered an enduring sense of Korean identity and patriotism even after almost a century of foreign dominance. On the other hand, scholars of China and the Mongol Empire have often overlooked Wang Ki's policies as mere aberrations of a collateral Chinggisid polity. David M. Robinson's Korea and the Fall of the Mongol Empire breaks through this intellectual impasse by telling a story of Wang Ki's life through the shifting notion of “alliance.” The concept of “alliance” here is primarily hierarchical with reciprocal obligations. The king of a lesser power like Wang Ki was to serve the empire when called upon, and the Mongol emperor was to protect the lesser polities like Koryŏ with his might.

The book begins with what Wang Ki experienced before his enthronement. He lived in the Mongol Empire's capital (today's Beijing) from 1341 to 1351 and experienced firsthand how the late Mongol Empire operated. Although increasingly affected by armed rebellions and natural disasters, the Mongols still exerted immense power in fending off challengers and responding to natural calamities, including a massive public works project that returned the Yellow River to its original course. Wang Ki also witnessed how the politics at the Mongol court exerted a direct influence upon what happened in the lesser polities that surrounded it. What happened at the Mongol court had immediate repercussions in Koryŏ—the emperor even dethroned some of Wang Ki's predecessors.

But by the time Wang Ki became king, the alliance between Koryŏ and the Mongol Empire demanded change, as the Chinggisid power started to falter and could no longer hold its end of the bargain. Not only did the Mongols increasingly become unable to suppress the rebels, but the Mongols also did not aid Koryŏ when the Red Turbans invaded Korea twice in 1359 and 1361. The Mongol military power remained substantial even after its expulsion from Beijing in 1368, as seen in the massive Mongol victories against the Ming forces in 1372 that partly reversed their previous losses. But Wang Ki felt he needed to explore other options without abandoning his relationship with the Mongols. In this sense, Wang Ki's seemingly contradictory actions are understandable. His “anti-Yuan” policies dating from 1356, which included constant contact with the purported rebels to the empire alongside his public claims of loyalty to the Mongol throne, were part of the recalibrations of alliances that simultaneously played out across much of Eurasia. Wang Ki maintained his contacts with the Mongols even after formally switching his allegiance to the Ming in 1370. Modern-day historians have not sufficiently captured this larger historical perspective. Wang Ki's story, in this sense, is representative of a broader Eurasian pattern of alliance recalibration.

Lastly, this reviewer commends Robinson for his impressive command of source materials and scholarships in different languages in producing this book. Many scholars have attempted to write histories that overcome national boundaries in creating broader, more comprehensive perspectives. But many have failed at such bids. For example, historians of China working on Sino-Korean relations are not necessarily limited in their linguistic ability to read the primary sources in Korean history. But many have struggled or did not bother to understand and absorb the growing body of secondary literature written in Korean, while just barely keeping up with the scholarly literature written in Japanese. Many have created skewed pictures in which one country stays active while the other stays passive.

Where many have slumped, however, Robinson has succeeded. He has taken the extra steps (and years) to learn the necessary languages and bodies of scholarship at universities in different countries. His work thereby engages with the scholarly tendencies and debates in the fields of Korean, Chinese, and Mongolian history. Moving beyond perspectives limited to just one of these fields, Robinson has created a narrative that puts the story of Wang Ki and his country within the larger historical context of shifting interests and alliances in East Asia. Robinson has established himself as a premier historian of this period, and this book is an outstanding addition to an already impressive catalog of works to his name.