. Toon (
Ferdows),
Qaen and
Tabas are the cities indicated in
Quhistan (Nowadays South Khorasan Province).
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 and Turkmens brought changes to the region time and time again. Ancient geographers of Iran divided Iran ("Iran-Shahr") 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 the residence of the Aryan tribes after entering Iran. The
Parthian empire was based near
Merv in Khorasan for many years. At Parthians times,
Esfarayen was one of the important villages of
Nishapur. During the
Sassanid dynasty, the province was governed by a
Spahbod (Lieutenant General) called "Padgoosban" 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 Islamic Arabs invaded Khorasan. The territory remained in the hands of the
Abbasid clan until 820, followed by the rule of the Iranian Taherid clan in the year 896 and the
Samanid dynasty in 900.
Mahmud of Ghazni conquered Khorasan in 994 and in the year 1037
Toghrül, the first of the
Seljuq empire rulers conquered Nishapur. Mahmud of Ghazni retaliated against the invaders several times, and finally the Ghaznavids defeated
Sultan Sanjar. But there was more to come, as in 1157 Khorasan was conquered by
the Khwarazmids and because of simultaneous attacks by the Mongols, Khorasan was annexed to the territories of the Mongol
Ilkhanate. In the 14th century, a flag of independence was hoisted by the
Sarbedaran movement in
Sabzevar, and in 1468, Khorasan came into the hands of
Tamerlane and the city of
Herat was declared as the capital. In 1507, Khorasan was occupied by
Uzbek tribes. After the death of
Nader Shah in 1747, parts of it were occupied by the Afghans for a short period. In these periods, Birjand was a small part of
Quhistan which almost encompasses the borders of present-day South Khorasan. The main cities of Quhistan were Toon (now
Ferdows) and
Qaen. Birjand grew in recent centuries, especially during the
Qajar dynasty and found its important role in this region. This region was a place of refuge for some movements like the
Ismaili, and was the target of Arab refugees who escaped from the tyranny of the
Abbasid caliphate. Zoroastrian vestiges also exist in the area. 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
Anglo-Persian War. In 1857 hostilities between the Persians and the British ended after the
Treaty of Paris was signed, and the Persian troops withdrew from Herat. Afghanistan reconquered Herat in 1863 under
Dost Muhammad Khan, two weeks before his death. This new province is but the old
Quhistan which was included into
greater Khorasan in the Iranian administrative planning. However, historically Qohistan forms a separate entity, with a distinct culture, history, environment and ecology. South Khorasan is one of the three provinces that were created after the division of
Khorasan in 2004. While at the beginning, the newly created "South Khorasan" included only
Birjand County and some new counties detached from that county (i.e.
Nehbandan,
Darmian and
Sarbisheh), in subsequent years, all northern and western cities and territories of the old Quhistan (such as
Qaen,
Ferdows and
Tabas) have been annexed into South Khorasan, which as of 2016 consists of 11 counties. Khorasan was the largest province of Iran until it was divided into three provinces on 29 September 2004. The provinces approved by the
parliament of Iran (on 18 May 2004) and the
Council of Guardians (on 29 May 2004) were
Razavi Khorasan,
North Khorasan, and South Khorasan. == Demographics ==