Mongol Conquest of the Khwarazmian Empire (1219-1221)

The Mongol conquest of the Khwarazmian Empire was the campaign of 1219–1221 in which Genghis Khan destroyed the most powerful Muslim state of Central Asia and eastern Iran. Provoked by the massacre of a Mongol-sponsored caravan at Otrar, Mongol armies captured Bukhara, Samarkand, Urgench, Merv and other great cities, and the shah died a fugitive. The war brought the Mongols into the Islamic world and became one of the most destructive episodes of the Middle Ages.

Background

The Khwarazmian Empire was ruled by the Khwarazm-shahs, a dynasty of Turkic origin based in Khwarazm on the lower Amu Darya. Under Ala al-Din Muhammad II (r. 1200–1220) it expanded rapidly, taking Transoxiana with Bukhara and Samarkand, most of Iran and much of Afghanistan. It was large and rich but young and divided: the shah quarrelled with his powerful mother Terken Khatun and with the Abbasid caliph, and his army relied on Turkic troops of uncertain loyalty.

After Genghis Khan’s rise and the Mongol conquest of the Qara Khitai realm in 1218, the two empires shared a border. Genghis Khan, still at war with the Jin in China, appears at first to have wanted trade with the shah rather than conflict.

The Otrar massacre

In 1218 a large caravan of Muslim merchants, reportedly about 450 people, travelled under Mongol protection to the Khwarazmian frontier town of Otrar on the Syr Darya. The governor, Inalchuq (also called Ghayir Khan), a relative of Terken Khatun, accused them of spying, seized their goods and had them killed, apparently with the shah’s approval. Genghis Khan sent envoys to demand that Inalchuq be handed over. The shah had one envoy executed and the others humiliated, and war became certain.

The campaign of 1219–1220

Genghis Khan led his army west in 1219. Estimates of its size range from about 100,000 to 200,000 men, including allied and auxiliary troops. Muhammad II chose not to fight a field battle, instead distributing his forces among the cities, a decision that allowed the Mongols to isolate and take them one by one.

The Mongols divided their army. Genghis Khan’s sons Chagatai and Ögedei besieged Otrar, which held out for about five months before falling in early 1220; Inalchuq was captured and put to death. Jochi moved down the Syr Darya, and other forces took Khujand. Genghis Khan himself, with his youngest son Tolui, crossed the Kyzylkum desert and appeared before Bukhara, which surrendered in February 1220. The citadel garrison was killed and the city burned. The historian Juvaini, writing a generation later, reports that Genghis Khan rode into the Friday mosque and then addressed the townspeople at the city’s festival prayer ground, calling himself a punishment sent by God for their sins.

Samarkand, the new capital, fell in March 1220 after a short siege, when part of its garrison surrendered. The Turkic soldiers who had changed sides were killed, the population was looted, and tens of thousands of craftsmen and young men were taken for labour and military service.

The fall of the shah and of Khorasan

The shah fled west across Iran. Genghis Khan sent his generals Jebe and Subutai in pursuit, and Muhammad II died, apparently of illness, on an island in the Caspian Sea in late 1220 or early 1221. Jebe and Subutai continued through north-western Iran and the Caucasus, defeating the Georgians, and in 1223 they routed the Rus princes and Cumans at the Kalka River, an early warning of the later Mongol invasion of Kievan Rus.

Urgench (Gurganj), the old capital of Khwarazm, resisted a long siege by Jochi, Chagatai and Ögedei, whose quarrels slowed operations. It fell in 1221, and chroniclers say the Mongols broke the dams of the Amu Darya and flooded the ruins. In early 1221 Tolui led an army into Khorasan. Merv surrendered and its people were massacred; Nishapur was destroyed in April 1221 after Genghis Khan’s son-in-law Toquchar was killed in an earlier attack on the city; Herat surrendered.

The shah’s son Jalal al-Din Mingburnu rallied troops in Afghanistan and defeated a Mongol army at Parwan in 1221. Genghis Khan pursued him and crushed his army on the banks of the Indus in late 1221; Jalal al-Din escaped by swimming his horse across the river into India.

The scale of destruction

The contemporary Arab historian Ibn al-Athir described the invasion as one of the greatest calamities ever to befall humanity. Juvaini and later writers give figures such as 1.3 million dead at Merv, and other chroniclers give comparably huge totals for Nishapur and Herat. Historians regard these numbers as impossible in detail, as the cities could not have held such populations, but agree that killing, deportation and the collapse of irrigation systems caused a catastrophic loss of population in Khorasan and Transoxiana. Some cities recovered within decades; others, such as Merv, never regained their former importance.

Key people

• Genghis Khan: directed the campaign and the attack on Bukhara in person.
• Ala al-Din Muhammad II: Khwarazm-shah whose refusal to give justice for Otrar led to war.
• Jalal al-Din Mingburnu: the shah’s son, who led resistance until 1231.
• Jebe and Subutai: the generals who pursued the shah and rode around the Caspian.
• Inalchuq: governor of Otrar, responsible for the massacre of the caravan.

Legacy

After the conquest, Transoxiana was placed under Mongol governors. The Khwarazmian merchant Mahmud Yalavach and his son Mas’ud Beg, Muslims who served the Mongols, administered the settled lands and helped restore trade and taxation. The region later formed the core of the Chagatai Khanate, ruled by descendants of Genghis Khan’s second son, while Iran became the heart of the Ilkhanate founded by his grandson Hülegü in the 1250s.

The conquest also scattered Khwarazmian soldiers across the Middle East. Bands of them served as mercenaries in Syria and Egypt, and in 1244 a Khwarazmian force sacked Jerusalem, an event that helped prompt the Seventh Crusade. In Central Asia, Bukhara and Samarkand recovered over the following century, and Samarkand later rose to new splendour as the capital of Timur in the late 14th century.

Myths and facts

• Myth: The Mongols killed everyone in every city they took. Fact: Treatment varied. Cities that resisted, such as Nishapur and Urgench, suffered massacres, but craftsmen were usually spared and deported, and some towns that surrendered quickly escaped the worst.
• Myth: Inalchuq was executed by having molten silver poured into his eyes and ears. Fact: The story is famous but appears only in some later accounts and cannot be confirmed; the sources agree only that he was put to death after Otrar fell.
• Myth: The war was caused by Mongol greed alone. Fact: Genghis Khan certainly sought expansion, but the immediate cause was the killing of his merchants and envoys, an offence that steppe custom treated as demanding revenge.

Timeline

• 1218: Mongols conquer Qara Khitai; the caravan is massacred at Otrar.
• 1219, autumn: Genghis Khan’s army reaches the Syr Darya and besieges Otrar.
• 1220, February: Bukhara falls.
• 1220, March: Samarkand falls.
• 1220–1221, winter: Muhammad II dies on a Caspian island.
• 1221, February–April: Merv, Nishapur and Urgench fall.
• 1221, late: Genghis Khan defeats Jalal al-Din on the Indus.
• 1223: Jebe and Subutai win at the Kalka River.

Why it matters

The conquest destroyed the leading power of the eastern Islamic world in barely three years and opened Iran, the Caucasus and the western steppe to the Mongols. It led to the creation of Mongol rule in Iran, culminating in the siege of Baghdad in 1258, and left a lasting memory of devastation in the histories of Central Asia and Iran.