Introduction: The Mongol Empire and the Institutional Foundations of Eurasian Integration

The year 1219 CE marked a turning point not just for the Khwarazmian Empire, but for the entire Eurasian landmass. A year earlier, a Sogdian merchant named Mahmud al-Tusi had set out from his home city of Bukhara on a trade mission to the Song dynasty capital of Lin’an (modern Hangzhou), carrying a cargo of Persian carpets, Central Asian horses, and glassware. His journey would take him through the territories of three rival states: the Khwarazmian Empire, the Qara Khitai, and the Western Xia, each levying separate tariffs, requiring separate travel permits, and enforcing separate legal codes. Midway through his trip, his caravan was attacked by a band of Khwarazmian border guards, who stole half his goods and left him for dead in the desert. Mahmud’s ordeal was not unusual: for most of Eurasian history, cross-continental trade was a high-risk, high-cost venture, limited to a small number of experienced merchants willing to endure years of travel, arbitrary taxation, and violence. The Mongol conquests that began in 1206 would upend this fragmented system, creating for the first time in history a single political framework that spanned from the Pacific coast of Korea to the Danube River in Central Europe. At the core of this framework were two interlocking institutional innovations: the *yam* (站赤, the Mongol imperial relay and communication network) and the *Yasa* (大札撒, the Great Legal Code of the Mongol Empire), supported by the *kurultai* (忽里勒台, the imperial assembly) mechanism for power coordination and policy legitimation. This book argues that these institutions were not mere administrative appendages of Mongol military conquest, but deliberate, adaptive tools for integrating the diverse political, economic, and cultural systems of Eurasia into a single functional whole—laying institutional foundations that would shape Eurasian history for centuries after the Mongol Empire itself fragmented in the late 14th century.

Core Research Questions

The existing scholarly literature on the Mongol Empire has long been dominated by two opposing narratives: one framing the Mongols as uniquely destructive “barbarians” who razed cities and disrupted Eurasian civilization, and the other romanticizing the so-called *Pax Mongolica* as a golden age of cross-cultural exchange enabled by Mongol military hegemony. Both narratives, however, largely sidestep the question of how the Mongols were able to sustain a transcontinental empire for over a century, governing territories that included sedentary agrarian civilizations, nomadic pastoralist confederations, Islamic city-states, and European feudal kingdoms, each with their own distinct legal traditions, economic systems, and cultural norms. This book addresses three interconnected research questions that have remained understudied in existing scholarship: 1. To what extent were the *yam* system and *Yasa* distinct institutional innovations, rather than mere adaptations of earlier steppe or sedentary imperial administrative practices? How did their cross-cultural design allow them to function across the full geographic and cultural span of the Mongol Empire? 2. How did these institutions reduce transaction costs for merchants, travelers, and officials across Eurasia, enabling levels of cross-continental trade, technological transfer, and cultural exchange that were unprecedented in pre-modern history? 3. What was the long-term legacy of these Mongol institutions for subsequent Eurasian empires, and what lessons do they hold for understanding the institutional foundations of cross-regional integration in the pre-modern and modern eras?

To answer these questions, this volume draws on a multilingual corpus of primary sources, including Yuan dynasty Chinese court records, Persian chronicles such as Rashid al-Din Hamadani’s *Jami‘ al-Tawarikh* (Compendium of Chronicles), European travel narratives by Marco Polo, William of Rubruck, and John of Plano Carpini, and newly published archaeological reports from *yam* station sites across Mongolia, China, Central Asia, and Russia. Unlike existing scholarship that often treats the Mongol Empire as a series of separate khanates (the Yuan dynasty, the Ilkhanate, the Chagatai Khanate, and the Golden Horde), this book analyzes the empire as a single integrated institutional system, while also accounting for the significant regional variation in how its core institutions were implemented and adapted to local conditions.

Existing Scholarly Debates: Beyond the “Destroyer vs. Unifier” Binary

Scholarly understandings of the Mongol Empire have evolved dramatically over the past century, moving from the overtly biased, Eurocentric narratives of the 19th and early 20th centuries to more nuanced, evidence-based analyses in recent decades. To contextualize this book’s contribution, it is necessary to first map the three dominant schools of thought in existing Mongol Empire scholarship, and identify the gaps this volume seeks to fill.

The Traditional “Mongol Destruction” School

The earliest modern scholarly accounts of the Mongol Empire, produced largely by European and Russian scholars in the 19th century, framed the Mongols as a uniquely destructive force that set back Eurasian civilization by centuries. Influenced by nationalist narratives of European superiority and the trauma of Mongol rule in Russia and Eastern Europe, scholars such as Henry H. Howorth and René Grousset portrayed the Mongols as little more than nomadic raiders with no capacity for institutional innovation. In Grousset’s famous 1939 work *The Empire of the Steppes*, the *yam* system is dismissed as a “simple military postal service” designed only to move troops and collect intelligence, with no broader economic or administrative function. The *Yasa* is similarly reduced to a collection of “barbaric” customary laws, including prohibitions on washing clothes in running water and stepping on thresholds, that were irrelevant to the governance of sedentary populations.

This narrative persists in popular understandings of the Mongol Empire to this day, but it fails to account for a wealth of contradictory evidence. For example, the 13th-century Persian historian Juvayni, who served in the Ilkhanate administration, explicitly notes that the *yam* system was used not just for military communication, but for the movement of merchants, pilgrims, and envoys, with official *paiza* (imperial tablets of authority) guaranteeing safe passage and free supplies at *yam* stations across the empire. Archaeological evidence from *yam* sites in modern-day Mongolia and Xinjiang also reveals standardized storage facilities for grain, fodder, and weapons, as well as administrative records showing systematic accounting of station supplies—features inconsistent with a purely ad hoc military postal service.

The *Pax Mongolica* Romanticization School

In reaction to the excesses of the destruction school, mid-20th century scholars such as Owen Lattimore and John Darwin framed the Mongol Empire as a precursor to modern globalization, creating a “Mongol Peace” that enabled unprecedented cross-cultural exchange across Eurasia. This narrative emphasizes the safety of the Silk Road under Mongol rule, the flow of goods, technologies, and ideas between East and West, and the cosmopolitan character of Mongol court culture, which employed administrators, scholars, and merchants from Chinese, Persian, Arab, and European backgrounds.

While this school corrected many of the biases of the earlier destruction narrative, it tends to overstate the coherence and intentionality of Mongol integration efforts. Many *Pax Mongolica* accounts treat the Mongol Empire as a unified, stable state that actively promoted trade and exchange, when in reality the empire was riven by internal conflict, regional autonomy, and frequent warfare between the four major khanates after the death of Möngke Khan in 1259. The *Pax Mongolica* narrative also tends to era