Mongol conquerors helped revive the very idea of a unified Iran
The Ilkhanate was founded by Hulegu, a grandson of Genghis Khan, yet its official name was simply Iran, the Land of Iran. Its Mongol rulers hired historians to cast them as heirs of the ancient Sasanian kings. They never meant to rebuild a nation, but the notion of Iran as one territory outlived them.
The groundwork was laid by force. In 1219 Genghis Khan declared war on the Khwarazmian ruler Muhammad II after he had Mongol-sent merchants killed, and within two years the major cities of the region were overrun. Later campaigns absorbed Georgia, Armenia and most of Persia, and victory at Köse Dağ in 1243 turned the Anatolian Seljuks into vassals.
Hulegu, brother of the Great Khans Möngke and Kublai, was sent west in the 1250s with a fifth of the Mongol army. He destroyed the Nizari Ismaili state in 1256 and the Abbasid Caliphate in 1258, then declared himself ilkhan, a subordinate khan. He brought Chinese scholars and astronomers with him, from whom the Persian astronomer Nasir al-Din al-Tusi learned Chinese calculation methods, and an observatory rose at Maragheh. When Möngke died, Hulegu withdrew most of his forces, and a small contingent of around 10,000 left in Palestine lost to the Egyptian Mamluks at Ain Jalut.
The realm, centred on modern Iran, Azerbaijan and Turkey, was ringed by rivals. The Golden Horde to the north went to war with Hulegu in 1262, partly allying with the Mamluks, while the China-based Yuan dynasty stayed a friend and nominal overlord. Early rulers tolerated shamanism, Buddhism and Christianity; Tekuder became the first Muslim khan, and Arghun, who followed him, pushed back against Muslim influence. Financial troubles mounted, and one vizier's attempt to introduce Yuan-style paper money largely failed.
The decisive shift came with Ghazan, who in 1295 made Islam the state religion. Christians and Jews lost equal status, and Buddhists were at first told to convert or leave, though he later eased this. Conversion did not end the long fight with the Mamluks over Syria. The Black Death struck in the 1330s, and after the last ilkhan, Abu Sa'id, died in 1335, the state fell apart. The later Safavid Empire built further on the Land of Iran ideology.
Source: Ilkhanate
