Outside Ulaanbaatar today, a giant steel statue of Chinggis Khan on horseback rises some forty meters above the steppe. In Iran, Russia and parts of China, his name has long meant something very different. How should we judge an empire that killed on a colossal scale and also linked a continent?

How the khanates fell

The Ilkhanate collapsed quickly. Abu Said died without an heir in 1335, rival commanders raised puppet khans, and the realm broke into local dynasties. In China, the Yuan faced floods, famine, a collapsing paper currency and quarrels at court. Rebellions spread in the 1350s, and in 1368 rebels drove the Yuan out of Dadu. The Mongols withdrew to the steppe, where their khans, known as the Northern Yuan, kept fighting the Ming for generations. In the sixteenth century Altan Khan revived Mongol power and allied with the Tibetan Buddhist hierarchy; the title Dalai Lama comes from that alliance, since dalai is Mongolian for ocean.

The Chagatai Khanate split into western and eastern halves. In the west rose Timur, known in Europe as Tamerlane, a Turkic Muslim commander. Because he was not descended from Chinggis, he could not take the title khan. Instead he married a Chinggisid princess, called himself guregen, meaning "royal son-in-law," and ruled through puppet khans. His campaigns from the 1370s to his death in 1405 rivaled the Mongols in destruction. Babur, who claimed descent from both Timur and Chinggis, founded the Mughal empire in India in 1526.

Russia and the "Tatar yoke"

The Golden Horde ruled the Rus lands indirectly. It did not occupy Russian towns but required princes to travel to Sarai to receive a yarlik, a khan's patent to rule, and to collect tribute. Moscow's princes rose partly by serving as the khan's tax collectors, gathering wealth and authority in the process. The Horde was weakened by plague and civil war after the 1350s. In 1380 Prince Dmitry of Moscow defeated a Horde army at Kulikovo, though Moscow was sacked two years later. A century later, in 1480, on the Ugra River a standoff ended Moscow's tribute: the two armies faced each other across the water, and the Horde withdrew without a battle. Russians date the end of the "Tatar yoke" from this event. Successor states lasted far longer. The Crimean Khanate survived until Russia annexed it in 1783.

Russian historians long blamed the yoke for Russia's backwardness and autocracy. Others argue that the Mongols also gave Muscovy a model of centralized taxation, postal relays and census taking, and that later Russian rulers borrowed freely. The debate is partly about evidence and partly about national self-image.

Weighing the empire

The death toll of the conquests cannot be measured precisely. Medieval figures are inflated, and modern estimates for the whole period vary widely, often in the tens of millions, with large uncertainty about how many died from violence, famine, flight or disease. Northern China's registered population fell dramatically between the late Jin and early Yuan counts, though part of that fall reflects people escaping the tax rolls rather than dying. In Iran, underground irrigation channels called qanats were damaged in places, and some regions took centuries to recover.

The other side of the ledger is real too: religious tolerance unusual for its age, promotion by merit, and connections that moved technologies and knowledge across Eurasia. Mongol armies used Chinese gunpowder weapons in some campaigns, and knowledge of gunpowder may have traveled west with them, though how much the Mongols themselves spread it is disputed. Since the 1990s some popular writers have presented Chinggis as a maker of the modern world, an image critics call romantic. Most historians now take a middle path, holding destruction and exchange together rather than letting one erase the other. Judged by the principle that every person has equal worth and must never be treated merely as a means, the deliberate massacre of civilians was a crime whatever trade followed. That judgment does not stop us studying how the system worked or what grew from it.

Memory in Mongolia

Under the communist government, which was closely tied to the Soviet Union, public celebration of Chinggis was discouraged. In 1962 a commemoration of the 800th anniversary of his birth drew condemnation from Moscow, and a senior official who promoted it, Tomor-Ochir, was removed from power. After the democratic revolution of 1990, Chinggis became a central symbol of Mongolian national identity. His face appears on banknotes, and the country's main airport bears his name.

Worked example: two exhibitions

Suppose a museum in Iran and a museum in Mongolia each plan an exhibition on the thirteenth century. The Mongolian curators want to show Chinggis as a founder and lawgiver; the Iranian curators want to remember the destruction of Nishapur. A good historian could help both. She would insist that each exhibition include evidence that complicates its story: the massacres for one, the tax exemptions, the yam and the scholars of Maragha for the other. The two exhibitions need not agree on a final verdict. Each must be honest about what the evidence shows and must treat the victims, on every side, as people whose lives mattered.