Abarshahr or Aparshahr was a satrapy (province) of the Sassanid Empire now located in Nishapur.
Neysabur or Naysabur was named Abarshahr during the Muslim occupation of Khorasan and Nishapur, and was the city's official name during the Rashidun Caliphate, Umayyad Caliphate, and Abbasid Caliphate.