Tahirid dynasty
The city was founded in the 3rd century by Shapur I as a Sasanian satrapy capital. Nishapur later became the capital of Tahirid dynasty and was reformed by Abdullah Tahir in 830, and was later selected as the capital of Seljuk dynasty by Tughril in 1037. From the Abbasid era to the Mongol invasion of Khwarezmia and Eastern Iran, the city evolved into a significant cultural, commercial, and intellectual center within the Islamic world. Nishapur, along with Merv, Herat and Balkh, were one of the four great cities of Greater Khorasan and one of the greatest cities in the middle ages, a seat of governmental power in the eastern of caliphate, a dwelling place for diverse ethnic and religious groups, a trading stop on commercial routes from Transoxiana and China, Iraq and Egypt.