Genghiz Khan and Timur
The Khorezmshahs were, however, to find themselves pitted against a terrible foe, the Mongols of Genghiz Khan. The latter initially toyed with the establishment of commercial contacts with the Khorezmshahs. But in 1218 a caravan of merchants with a Mongol envoy was put to death at the Khorezm border town of Otrar. Genghiz Khan prepared for war. The Khorezmshah Mohammed II adopted a defensive strategy based around his fortified towns. They were sacked one after the other. Gurganj was taken in April 1221, and most of the inhabitants massacred. A similarly brutal fate met the citizens of Merv. The oldest son of Mohammed II, Jelaladdin, secured a reputation for valiant resistance against the Mongols in theatres from Afghanistan to Azerbaijan, until his death in 1231. But this was but a minor nuisance to the all-conquering Mongols.
Mongol dominance of the region brought a long period of relative peace, and the revival of trade. This was the period of Marco Polo's travels to China. Some cities, however, including Merv, were never fully to recover from the severity of their sacking.
A future leader whose notoriety is almost as great as that of Genghiz Khan was born in 1336 into the Barlas clan of Shakhrisabz, near Samarkand. Timur, known in the west as I'amerlane ('Timur the lame'), became the ruler of Samarkand in 1370. Claiming ancestry from Genghiz Khan, he was to conduct 30 years of almost continuous campaigning. His actions could be hugely brutal, for example in his razing of Urgench, in part motivated by the consideration that the Khorezm Oasis represented a rival caravan route to that centred on his heartland of Samarkand and Bukhara. Timur's death ushered in a struggle for power between his sons and relatives. His fourth son, Shah Rukh, based in Herat, emerged the strongest. Shah Rukh established a new city at Merv, Abdullah Khan Kala. But within a few years of his death in 1447, the Timurid Empire had collapsed.