Seljuks, Mongols and Ilkhanids

In 1040, at Dandanaqan, near Merv, Turkic nomads led by the Seljuk family defeated the army of the Ghaznavid sultan. Fifteen years later their leader, Tughril Beg, entered Baghdad and was recognised by the caliph as sultan. The Seljuks were Turks, but they governed in Persian, through Persian officials, and they carried Persian as a language of culture deep into Anatolia.

The most famous of those officials was Nizam al-Mulk, vizier to the sultans Alp Arslan and Malikshah for some three decades. He founded colleges known after him as the Nizamiyya and wrote a book of advice on government, the Siyasatnama. He was murdered in 1092, a killing traditionally blamed on the Nizari Ismailis, known to their enemies as the Assassins, who held mountain fortresses such as Alamut in the Alborz.

Builders and destroyers

Seljuk Isfahan was a capital of building and of science. In its Friday Mosque, the Masjed-e Jameh, two brick domes from the 1080s survive, the smaller northern one admired for the precision of its geometry. Malikshah gathered astronomers, among them Omar Khayyam, to reform the calendar. The result, the Jalali calendar, is an ancestor of the solar calendar used in Iran today. Abroad, Khayyam is known for the quatrains, robā'i, attributed to him, though how many he really wrote is much debated.

In 1219 the Mongols under Genghis Khan invaded the eastern Islamic world. Cities that resisted, among them Merv and Nishapur, were destroyed and their people massacred; the chroniclers' figures are thought to be exaggerated, but the scale of the devastation is not in doubt. In 1256 Genghis's grandson Hulagu took Alamut, and in 1258 he sacked Baghdad and put the last Abbasid caliph to death. The young Jalal al-Din Rumi, born in Balkh, had already left the east with his family and spent his life in Konya, in Anatolia. Hulagu's descendants, the Ilkhanids, ruled Iran from Maragheh and Tabriz. In 1295 the Ilkhan Ghazan converted to Islam. His vizier Rashid al-Din compiled the Jami' al-Tawarikh, 'Compendium of Chronicles', an ambitious history of the known world whose illustrations show Chinese influence. Ghazan's brother Öljeitü built a new capital at Soltaniyeh, where his mausoleum's great dome still rises over the plain. After the death of the Ilkhan Abu Sa'id in 1335, the state broke apart.