Nishapur County is in Razavi Khorasan province, Iran. Its capital is the city of Nishapur, the second largest city in the province and the third largest city in Eastern Iran. The Nishapur massacre by the Mongols took place at Nishapur in April of 1221. The Mongol armies of Genghis Khan massacred the entire population of the area, which some estimates put at 1,747,…Nishapur County is in Razavi Khorasan province, Iran. Its capital is the city of Nishapur, the second largest city in the province and the third largest city in Eastern Iran. The Nishapur massacre by the Mongols took place at Nishapur in April of 1221. The Mongol armies of Genghis Khan massacred the entire population of the area, which some estimates put at 1,747,000 citizens.