The Fall of the Mongol Empire

The Mongol Empire did not collapse in a single event. Its decline was a long, drawn-out process that took almost three centuries to complete, from the first signs of fragmentation in the mid-13th century to the final disappearance of the last successor khanate in the 17th century. The causes of the decline were many: the absence of a clear law of succession, the difficulty of maintaining a single political framework across a continent-sized empire, the cultural assimilation of the khanates into their subject populations, the rise of new regional powers, and the gradual transformation of the steppe environment that had originally produced the Mongol conquests. The “fall” is best understood as the combined effect of these pressures acting over a long period, not as a single event.

The fall of the empire can be divided into three broad phases. The first phase, from the 1260s to the 1330s, saw the fragmentation of the unified empire into four semi-independent khanates, each with its own political and cultural trajectory. The second phase, from the 1330s to the 1360s, saw the collapse of the Ilkhanate and the Yuan Dynasty, the two khanates that had been most deeply involved in the cultures of their subject populations. The third phase, from the 1360s to the 17th century, saw the gradual absorption of the remaining khanates by new regional powers, including the Ming Dynasty in China, the Grand Duchy of Moscow in Russia, and the Timurid Empire in Central Asia.

The First Phase: Fragmentation (1260–1335)

The first phase of the decline began with the Toluid Civil War of 1260 to 1264. The civil war, which was fought between Kublai Khan and his younger brother Ariq Böke (with Hulagu on Kublai’s side), was the first major conflict within the Mongol ruling class since the death of Genghis Khan, and it marked the end of the political unity of the empire. The war resulted in a Toluid victory, but it also established the precedent that the great khan would have to be a Toluid and that the khanate of Persia, which had been founded by Hulagu, would be a semi-independent state. (The standard academic reading, e.g., Allsen 2001, is that the real moment of fragmentation was the death of Möngke in 1259 and the resulting double kurultai of 1260 — at Karakorum, which elected Ariq Böke, and at Khanbaliq, which elected Kublai — and the civil war was the working-out of that split.)

The fragmentation was further entrenched by the death of Kublai Khan in 1294. Kublai’s successors as great khan were able to maintain the appearance of imperial unity, but the four khanates were increasingly pursuing their own interests. The Golden Horde and the Ilkhanate fought a long series of wars in the Caucasus in the 1260s, 1270s, and 1280s — the Berke–Hulagu war of 1262 was the first civilizational Mongol-on-Mongol war in the western steppe — and the two khanates were so hostile to each other that they took different sides in the broader politics of the Islamic world. The Ilkhanate allied with the Christian Crusader states and was a bitter enemy of the Mamluk Sultanate of Egypt; the Golden Horde, after its conversion to Islam under Berke Khan, became a close ally of the Mamluks.

The cultural and religious differences between the khanates also became more pronounced during this period. The Yuan Dynasty under Kublai and his successors was a centre of Tibetan Buddhism, with a strong Chinese bureaucracy and a sophisticated cosmopolitan culture. The Ilkhanate gradually converted to Islam in the late 13th and early 14th centuries (formally under Ghazan Khan in 1295), and the conversion was largely driven by the political need to win the support of the Muslim majority of the population. The Golden Horde, after its conversion to Islam in the early 14th century, became a major centre of Islamic culture, with the city of Sarai on the lower Volga serving as a major centre of Islamic learning. The Chagatai Khanate remained culturally conservative and religiously mixed, with both Buddhist and Muslim populations in its territory.

The Second Phase: Collapse (1335–1368)

The second phase of the decline began with the collapse of the Ilkhanate in 1335. Abu Sa’id, the last effective Ilkhan, died without a clear heir, and the Ilkhanate broke up into a number of successor states (the Jalairid, the Chobanid, the Muzaffarid, the Kartid, the Sarbedar). The collapse of the Ilkhanate was a major blow to the Mongol world: the Ilkhanate had been the wealthiest and most sophisticated of the khanates, and the home of the Maragheh Observatory, the Jami’ al-Tawarikh of Rashid al-Din, and the Rab’-e Rashidi academy. The collapse of the Ilkhanate also marked the end of Mongol rule in Persia and the beginning of a long period of political fragmentation in the Middle East.

The collapse of the Ilkhanate was followed, three decades later, by the collapse of the Yuan Dynasty. The Yuan Dynasty had been weakened by a long period of internal unrest, including the corruption of the later Yuan emperors, the burden of maintaining a large and expensive imperial establishment, and the strain of repeated natural disasters, including the Yellow River floods of 1344 and the Black Death of the 1330s and 1340s. The Red Turban Rebellion, which began in the 1350s in southern China and spread north, brought the Ming Dynasty to power. Zhu Yuanzhang captured Khanbaliq in 1368 and expelled the last Yuan emperor, Toghon Temür, who fled to Mongolia and continued to rule the northern territories as the Northern Yuan.

The collapse of the Yuan Dynasty was a major turning point in the history of the Mongol world. It marked the end of Mongol rule in China, and it marked the beginning of a long period in which the Mongol heartland was no longer the centre of a vast empire. The Northern Yuan survived until the 17th century, but it was increasingly peripheral to the major political events of Eurasia.

The Third Phase: Absorption (1368–1700s)

The third phase of the decline was the absorption of the remaining khanates by new regional powers. The Golden Horde, which had survived the collapse of the Ilkhanate and the Yuan Dynasty, gradually declined in the late 14th and 15th centuries. The Horde was weakened by internal divisions, including the split between the White Horde and the Blue Horde in the mid-14th century and the rise of separate Tatar khanates in the Crimea, Kazan, and Astrakhan. The Grand Duchy of Moscow, which had been a tributary of the Golden Horde, gradually emerged as the major power in the Russian steppes, and in 1480, the Grand Duke Ivan III declared independence from the Horde in the Great Stand on the Ugra River — conventionally dated as the moment of Russian independence from the Mongols. The Horde was finally broken by the Crimean Khanate and the Grand Duchy of Moscow in 1502. (The Crimean Khanate, a successor of the Golden Horde, was itself absorbed by the Russian Empire only in 1783.)

The Chagatai Khanate, which had survived the collapse of the Ilkhanate, was absorbed by the empire of Timur in the late 14th century. Timur, a Barlas Turk who claimed descent from Chagatai, conquered the western part of the khanate in the 1360s and went on to build a vast empire that, at its height, stretched from Delhi to Anatolia. The Timurid Empire was a major patron of Islamic culture, and it was the last great Central Asian empire of the medieval period. The Timurid Empire gradually declined in the 15th and 16th centuries, and the eastern part of the Chagatai Khanate was eventually absorbed by the Yarkand Khanate and the Kazakh Khanate. The Timurid cultural legacy, however, persisted in the Mughal Empire of India (founded 1526 by a Timurid prince, Babur).

The Northern Yuan survived in Mongolia until the 17th century, when it was finally incorporated into the Manchu Qing Empire. The last khan of the Northern Yuan, Ligdan Khan, was defeated by the Manchus in 1634, and the Mongol ruling class was gradually integrated into the Qing imperial system. The Qing continued to recognize the Mongol nobility as a distinct political elite, and the Mongol territories of Inner and Outer Mongolia remained distinct administrative units within the Qing Empire until the fall of the Qing in 1911.

The Causes of the Decline

The causes of the Mongol decline have been debated for centuries. The principal explanations in modern scholarship are:

The absence of a clear law of succession. Genghis Khan had ordered that the great khan be elected by a kurultai, but he had not specified a single principle of succession. The default was election among Borjigin males, but the kurultai could not agree on whether the throne should follow primogeniture, fraternal rotation, or the support of the most powerful army. The result was a series of succession crises (1259–1260, 1294, 1335, 1368, 1502) that, each in their own way, weakened the khanate in question.
The difficulty of maintaining a single political framework across a continent-sized empire. The Mongol Empire at its height covered about 24 million square kilometres, from Korea to Hungary, and from the Arctic to the Persian Gulf. The communications technology of the 13th century could not support the political integration of so large a space. Distance, climate, and the absence of a single dominant language or culture all worked against centralization.
The cultural assimilation of the khanates into their subject populations. The Yuan, the Ilkhanate, and the Golden Horde all became, in time, more Chinese, more Persian, and more Turkic than they were Mongol. The Mongol ruling class intermarried with local elites, learned local languages, and adopted local customs. The process was slow, but it was the direction in which each khanate moved, and by the 14th century the Mongol character of the ruling class was thin in all four khanates.
Environmental and ecological factors. Some modern historians (e.g., Pederson et al. 2014, in Science) have argued that a series of droughts in the Mongol heartland in the late 13th and early 14th centuries weakened the central khanate by reducing the carrying capacity of the steppe. The argument is contested but has gained ground.

The most likely explanation is a combination of all four factors. The Mongol decline was the combined effect of political, ecological, and cultural pressures acting over a long period, and the eventual collapse of the empire was the result of a complex chain of events rather than a single cause.

The Legacy of the Decline

The fall of the Mongol Empire was a major turning point in the history of Eurasia. It marked the end of a period in which the political framework of the continent had been dominated by a single imperial system, and it marked the beginning of a long period in which the continent was divided into a number of competing regional powers. The fall of the empire also marked the end of the Pax Mongolica and the beginning of a long period in which the overland trade routes of Eurasia became more dangerous and less heavily used.

The legacy of the decline is still visible in the modern world. The successor states of the Mongol Empire — the modern states of China, Russia, Iran, and the Central Asian republics — all bear the imprint of the Mongol period, and the political frameworks established by the khanates continue to shape the political life of the modern world. The fall of the empire was, in a sense, the birth of the modern Eurasian political order.

Sources

Thomas T. Allsen, Commodity and Exchange in the Mongol Empire (Cambridge, 2001).
David Morgan, The Mongols (2nd ed., Oxford, 2007), ch. 7.
Peter Jackson, The Mongols and the West, 1221–1410 (London, 2005).
Timothy May, The Mongol Conquests in World History (London, 2012), ch. 9–10.
Marie Favereau, The Horde: How the Mongols Changed the World (Cambridge, MA, 2021), ch. 13–16.
Amy Chua, Day of Empire: How Hyperpowers Rise and Fall (New York, 2007), ch. 4 (popular treatment).
N. Pederson et al., “Pluvials, Droughts, the Mongol Empire, and Modern Mongolia,” Proceedings of the National Academy of Sciences 111 (2014): 4375–4379.