By the mid-14th century the great khanates founded by Genghis Khan's descendants — the Ilkhanate in Iran, the Chagatai in Transoxiana — had unravelled amid internal strife and plague. Into this vacuum stepped Timur (Turkic 'iron'; Persian Tîmûr-i Leng, 'Timur the Lame', in European languages Tamerlane), a member of the Barlas Turco-Mongol tribe of Transoxiana, who rose through military skill and marriage alliances. In 1370 he seized Samarkand and proclaimed his own state. Because he was not of Genghisid descent he used the title 'emir' rather than 'khan', but he married a Genghisid princess and bore the title küregen (son-in-law).

Over the next thirty-five years Timur crossed the heart of Eurasia. He struck Iran and Mesopotamia, the Caucasus, the Golden Horde, and in 1398 the Delhi Sultanate; the sack of Delhi was accompanied by the massacre of hundreds of thousands of civilians. In 1400-1401 he took Aleppo and Damascus and sacked Baghdad once more. At the Battle of Ankara in 1402 he captured the Ottoman sultan Bayezid I, plunging the Ottoman state into the decade-long Interregnum. Accounts record towers built from the skulls of victims in conquered cities; while some of this is exaggerated by hostile sources, modern historians broadly agree on the extreme scale of the violence.

The same Timur turned Samarkand into the spectacular stage of the age. From his campaigns he brought — through deportation or invitation — craftsmen to his capital: stonecutters, tile-workers, calligraphers, astronomers. The colossal iwan of the Bibi Khanym Mosque, the turquoise-tiled mausolea of the Shah-i-Zinda necropolis, and the madrasa and observatory later completed by his grandson Ulugh Beg are products of this period. Ulugh Beg (1394-1449) built an observatory at Samarkand and measured stellar positions more accurately than most contemporary European work; his Zij-i Sultani was in use across the Islamic world and Europe for a century.

Timur died in 1405 while marching on China. The state quickly fragmented, but the Timurid cultural synthesis — Turco-Mongol military legacy, Persian literature and aesthetics, Islamic scholarship — survived another half-century at Herat and, through Babur, was carried to India in 1526 as the Mughal Empire. Reading Timur as merely a 'butcher' or, as his own court did, merely a 'civilising founder' is misleading; both are the same history.