North khorasan province is a province located in northeastern Iran. Bojnourd is the capital of the province. Greater khorasan has witnessed the rise and fall of many dynasties and governments in its territory throughout history. Various tribes of Persian, Arabs, Turks, Mongols, Turkmens, and Afghans have brought change to the region time and time again. Ancient geographers of Iran divided Iran into eight segment of which the most flourishing largest was the territory of Greater khorasan, Esfarayen among other cities of the province, was one of the focal points for settlement by Aryan tribes entering Iran. In the year 651, the army of Islamic Arabs invaded khorasan.