Soltaniyeh, located some 240 kilometres (150 mi) to the north-west of Tehran, was built as the capital of Mongol Ilkhanid rulers of Iran in the 14th century.

Soltaniyeh was visited by Ruy González de Clavijo, who reported that the city was a hub of silk exportation.

William Dalrymple notes that Öljaitü intended Soltaniyeh to be "the largest and most magnificent city in the world" but that it "died with him" and is now "a deserted, crumbling spread of ruins.

[9] The 2016 census measured the population of the city as 7,638 people in 2,319 households,[2] by which time the district had been elevated to the status of Soltaniyeh County.

In 1329, the Latin Diocese of Samarcanda became its suffragan for the Chagatai Khanate, at least until Tamerlane (founder of the Timurids) swept its see Samarkand.