Razavi Khorasan Province (, Ostân-e Xorâsân-e Razavi) is one of the 31 provinces of Iran, located in northeastern Iran. The city of Mashhad is the center and capital of the province. Razavi Khorasan is one of the three provinces that were created after the division of Khorasan province in 2004. In 2014 it was placed in Region 5 with Mashhad as the location of the region's secretariat. At the time of the National Census of 2006, the province had a population of 5,515,980 in 1,426,187 households. The following census in 2011 counted 5,994,402 people in 1,716,314 households. At the latest census conducted in 2016, the population had risen to 6,434,501 in 1,938,703 households. History The Greater Khorasan has witnessed the rise and fall of many dynasties and governments in its territory throughout history. Various tribes of the Arabs, Turks, Kurds, Turkmens, and Mongols brought changes to the region time and time again. Ancient geographers of Iran divided Iran ("Ērānshahr") into eight segments of which the most flourishing and largest was the territory of Greater Khorasan. Esfarayen, among other cities of the province, was one of the focal points for residence of the Aryan tribes after entering Iran. The Parthian Empire was based near Merv in Khorasan for many years. During the Sassanid dynasty, the province was governed by a Spahbod (Lieutenant General) called "Padgošban" and four margraves, each commander of one of the four parts of the province. Khorasan was divided into four parts during the Muslim conquest of Persia, each section being named after the four largest cities, Nishapur, Merv, Herat, and Balkh. In the year 651, the army of the Rashidun Caliphate conquered Khorasan. The territory remained under the rule of the Abbasid Caliphate until 820, followed by the rule of the Iranian Tahirid dynasty until 873, and the Samanid dynasty in 900. Mahmud of Ghazni conquered Khorasan in 994, and Tuğrul in the year 1037. In 1507, Khorasan was occupied by the Uzbek tribes. After the death of Nader Shah in 1747, it was occupied by the Afghan Durrani Empire centered in Qandahar. In 1824, Herat became independent for several years when the Afghan Empire was split between the Durranis and Barakzais. The Persians sieged the city in 1837, but the British assisted the Afghans in repelling them. In 1856, the Persians launched another invasion and briefly managed to recapture the city; it led directly to the