Which Central Asian conqueror built a pyramid of skulls at Isfahan?

Timur - Tamerlane in English, from Timur-e Lang, Timur the Lame - took Isfahan in 1387 on terms. The city then rose against his tax collectors and killed them. He came back, and the chroniclers report something like seventy thousand heads built into towers around the walls. He did the same or worse at Delhi, at Baghdad and at Aleppo, and the practice was not incidental; it was policy, advertised in advance so the next city would open its gates.

He was not a Genghisid by blood, which mattered enormously in the world he lived in, so he never took the title of khan. He ruled through puppet descendants of Genghis, married into the line to earn the style of royal son-in-law, and campaigned almost continuously for thirty-five years without ever losing a battle.

The same man made Samarkand one of the most beautiful cities on Earth, deporting the finest craftsmen of every place he sacked in order to build it - the Bibi-Khanym mosque, the Registan, the ribbed turquoise dome over his own tomb. He was reportedly a strong chess player and enjoyed the company of scholars, including a famous and prickly meeting with the historian Ibn Khaldun outside Damascus.

In 1941 the Soviet anthropologist Mikhail Gerasimov opened the tomb and confirmed the sources: a tall man, injured in the right leg and right arm. The tomb is said to have carried a warning that whoever disturbed it would loose a still greater conqueror, and Germany invaded the Soviet Union days later. It is a very good coincidence, and that is all it is.