Khorasan, also written as Khurasan (Middle Persian: Khwarāsān, Persian: خراسان بزرگ or خراسان کهن listen (help·info)), is a historical region lying in the northeast of Persia. "In pre-Islamic and early Islamic times, the term "Khurassan" frequently had a much wider denotation, covering also parts of Central Asia and Afghanistan; early Islamic usage often regarded everywhere east of western Persia, sc. Djibal or what was subsequently termed 'Irak 'Adjami, as being included in a vast and ill-defined region of Khurasan, which might even extend to the Indus Valley and Sind."
Khorasan in its proper sense comprised principally the cities of Balkh, Herat, Taloqan, and Ghazni (now in Afghanistan), Mashhad, Nishapur, and Sabzevar (now in northeastern Iran), Merv and Nisa (now in southern Turkmenistan), and Samarqand and Bukhara (now in Uzbekistan). Some believe that at certain times Khorasan covered a wider area, which included parts of Transoxiana, Soghdiana, Sistan, and extended to the boundaries of the Indian subcontinent. When the Arabs first arrived to the southern Hindu Kush to defeat the Zunbils, they recognized it as al-Hind (Sind), owing to the prevalence of Buddhists and Hindus (non-Zoroastrians) due to its cultural connection with Greater India. Sources from the 14th to the 16th century report that areas in the south of the Hindu Kush mountain range (Zamindawar, Balochistan, and Kabulistan) formed a frontier between Khorasan and Hindustan.
In the Islamic period, Persian Iraq and Khorasan were the two important territories. The boundary between these two was the region surrounding the cities of Gurgan and Damghan. In particular, the Ghaznavids, Seljuqs, and Timurids divided their empires into Iraqi and Khorasani regions. The adjective Greater is added these days to distinguish the historical region from the Khorasan Province of Iran, which roughly encompasses the western half of the historical Greater Khorasan.
The name "Khorasan" is derived from Middle Persian khwar (meaning "sun") and āsān (or ayan literally meaning "to come" or "coming" or "about to come"), hence meaning "land where the sun rises" the same etymology also having been suggested for Khwarezm. The Persian word Khāvar-zamīn (Persian: خاور زمین), meaning "the eastern land", has also been used as an equivalent term.
First established as a political entity by the Sassanids in the 3rd century AD, the borders of the region have varied considerably during its 1600-year history. Initially the Khorasan province of Sassanid empire included the cities of Nishapur, Herat, Merv, Faryab, Taloqan, Balkh, Bukhara, Badghis, Abiward, Gharjistan, Tus or Susia, Sarakhs and Gurgan.
It acquired its greatest extent under the Caliphs, for whom "Khorasan" was the name of one of the three political zones under their dominion (the other two being Eraq-e Arab "Arabic Iraq" and Eraq-e Ajam "Non-Arabic Iraq or Persian Iraq"). Under the Umayyad and Abbasid caliphates, Khorasan was divided into four major sections or quarters (rub′), each section based on a single major city: Nishapur, Merv, Herat and Balkh.
In the Middle Ages, the term was loosely applied in Persia to all its territories that lay east and north east of Dasht-e Kavir and therefore were subjected to change as the size of empire changed. According to Ghulam Mohammad Ghobar, Afghanistan's current territories formed the major portion of Khorasan, as two of the four main capitals of Khorasan (Balkh, Merv, Nishapur and Herat) are now located in Afghanistan. Ghobar uses the terms "Proper Khorasan" and "Improper Khorasan" in his book to distinguish between the usage of Khorasan in its strict sense and its usage in a loose sense. According to him, Proper Khorasan contained regions lying between Balkh in the east, Merv in the north, Sistan in the south, Nishapur in the west and Herat, known as the Pearl of Khorasan, in the center. Improper Khorasan's boundaries extended to Kabulistan and Hazarajat in the east, Sistan and Baluchistan in the south, Transoxiana and Khwarezm in the north, and Damghan and Gorgan in the west. It is mentioned in the Memoirs of Babur that:
"The people of Hindustān call every country beyond their own Khorasān, in the same manner as the Arabs term all except Arabia, Ajem. On the road between Hindustān and Khorasān, there are two great marts: the one Kābul, the other Kandahār. Caravans, from Ferghāna, Tūrkestān, Samarkand, Balkh, Bokhāra, Hissār, and Badakhshān, all resort to Kābul; while those from Khorasān repair to Kandahār. This country lies between Hindustān and Khorasān."
Before the region fell to Alexander the Great in 330 BC, it was part of the Achaemenid Empire and prior to that it was occupied by the Medes. Following Alexander's brief occupation, the successor state of the Seleucid Empire controlled the area until 305 BCE when they gave south of the Hindu Kush to the Indian Maurya Empire as part of an alliance treaty.
"Alexander took these away from the Aryans and established settlements of his own, but Seleucus Nicator gave them to Sandrocottus (Chandragupta), upon terms of intermarriage and of receiving in exchange 500 elephants."—Strabo, 64 BC – 24 AD
The land that became known as Khorasan in geography of Eratosthenes was recognized as Ariana at that time, which made up Greater Iran or the land where Zoroastrianism was the dominant religion. The southeastern region of Ariana fell to the Kushan Empire in the 1st century AD. The Kushan rulers built a capital in modern-day Afghanistan at Bagram and are believed to have built the famous Buddhas of Bamiyan. Numerous Buddhist temples and buried cities have been found in Afghanistan. However, the region of Ariana (or Khorasan) remained predominantly Zoroastrian but there were also Manichaeists, sun worshippers, Christians, Pagans, Shamanists, Buddhists, Jews and others. One of the three great fire-temples of the Sassanids "Azar-burzin Mehr" is situated near Sabzevar in Iran. The boundary of the region began changing until the Kushans and Sassanids merged to form the Kushano-Sassanian civilization.
During the Sassanid era, Persia was divided into four quarters, Khvarvaran in the west, Bakhtar in the north, Arachosia in the south and Khorasan in the east, next to Sind or Hind. Khorasan in the east saw some conflict with the Hephthalites who became the new rulers in the area but the borders remained stable. Being the eastern parts of the Sassanids and further away from Arabia, Khorasan quarter was conquered after the remaining Persia. The last Sassanid king of Persia, Yazdgerd III, moved the throne to Khorasan following the Arab invasion in the western parts of the empire. After the assassination of the king, Khorasan was conquered by Arab Muslim troops in 647 AD. Like other provinces of Persia it became one of the provinces of Umayyad dynasty.
The first movement against the Arab invasions was led by Abu Muslim Khorasani between 747 and 750. He helped the Abbasids come to power but was later killed by Al-Mansur, an Abbasid Caliph. The first independent kingdom from Arab rule was established in Khorasan by Tahir Phoshanji in 821, but it seems that it was more a matter of political and territorial gain. Tahir had helped the Caliph subdue other nationalistic movements in other parts of Persia such as Maziar's movement in Tabaristan.
Other major independent dynasties who ruled over Khorasan were the Saffarids from Zaranj (861–1003), Samanids from Bukhara (875–999), Ghaznavids from Ghazni (963–1167), Seljuqs (1037–1194), Khwarezmids (1077–1231), Ghurids (1149–1212), and Timurids (1370–1506). It should be noted that some of these dynasties were not Persian by ethnicity. The periods of the Ghaznavids of Ghazni and Timurids of Herat are considered as some of the most brilliant eras of Khorasan's history. During these periods, there was a great cultural awakening. Many famous Persian poets, scientists and scholars lived in this period. Numerous valuable works in Persian literature were written. Nishapur, Herat, Ghazni and Merv were the centers of all these cultural developments.
From the 16th century to the early 18th century, Khorasan was ruled by the Shia Safavid dynasty while the region to the east by the Sunni Khanate of Bukhara and the southeast by the Sunni Mughul Empire. It was conquered in 1722, by the Ghilzai Afghans from Kandahar and became part of the Hotaki dynasty form 1722 to 1729. Nader Shah recaptured Khorasan in 1729 and chose Mashhad as the capital of Persia. Following the assassination of Nader Shah Afshar in 1747, A major part of Khorasan was annexed with the Durrani Empire, including Herat and Balkh. Mashhad was under control by the ancestor of Nader Shah, Shahrukh Afshar until 1796. In 1796, Agha Muhammad Khan conquered most parts of Khorasan, including Herat and Merv. Herat was annexed to Afghanistan from Persia in 1857 by the Treaty of Paris (1857). In 1881, the northern parts of Khorasan or Khwarezm areas, were annexed to Russian Empire by the Treaty of Akhal. 
Khorasan has had a great cultural importance among other regions in Greater Iran. The literary New Persian language developed in Khorasan and Transoxiana and gradually supplanted the Parthian language. The New Persian literature arose and flourished in Khorasan and Transoxiana where the early Iranian dynasties such as Tahirids, Samanids and Ghaznavids were based.The early Persian poets such as Rudaki, Shahid Balkhi, Abu al-Abbas Marwazi, Abu Hafas Sughdi, and others were from Khorasan. Moreover, Ferdowsi, the author of Shahnameh, the national epic of Greater Iran was also from Khorasan.
Until the devastating Mongol invasion of the thirteenth century, Khorasan remained the cultural capital of Persia. It has produced scientists such as Avicenna, Al-Farabi, Al-Biruni, Omar Khayyám, Al-Khwarizmi, Abu Ma'shar al-Balkhi (known as Albumasar or Albuxar in the west), Alfraganus, Abu Wafa, Nasir al-Din al-Tusi, Sharaf al-Dīn al-Ṭūsī, and many others who are widely well known for their significant contributions in various domains such as mathematics, astronomy, medicine, physics, geography, and geology.
In Islamic theology, jurisprudence and philosophy, and in Hadith collection, many of the greatest Islamic scholars came from Khorasan, namely Ahmad ibn Hanbal, Abu Hanifa, Imam Bukhari, Imam Muslim, Abu Dawood, Al-Tirmidhi, Al-Nasa'i, Al-Ghazali, Al-Juwayni, Abu Mansur Maturidi, Fakhruddin al-Razi, and others. Shaykh Tusi, a Shi'a scholar and Al-Zamakhshari, the famous Mutazilite scholar, also lived in Khorasan.
In Ali Soufan's book "The Black Banners", he explains the title by noting that quotes from various Hadiths regarding "Black Banners" of a "new army" taking over Khorasan have some kind of prophetic significance with many modern adherents of Jihadism. He notes that it is "not a coincidence" that Osama bin Laden made al-Qaeda's flag black. On the other hand, Afghanistan's national flag was black originally and even today it is one-third black, and with the help of the International Security Assistance Force (ISAF) is fighting against al-Qaeda. What is more interesting is that after Afghanistan, other Muslim nations with black in their flags began fighting against their rulers. This includes Iraq in 2003 against Saddam Hussain, Pakistan Peoples Party (PPP) against Pervaz Musharraf, and the latest Arab Spring in which a number of Arab rulers were deposed. Soufan also notes that there is debate about whether the prophet Mohammed actually spoke some of the quoted Hadiths (such as one attributed to Abu Hurairah). He also notes that Sheikh Salman al-Ouda has said the Black Banner hadiths are not able to be authenticated.
Khorasan was originally inhabited by the Parthian people, the ancestors of today's people of Afghanistan's western provinces and Iran's eastern provinces as well as parts of Turkmenistan.
The Parthian people appear to have been the first ethnic group to populate the region, but they began mixing with an increasing number of foreign invaders and as a result their proportionate number was reduced. Significant immigrants such as Arabs from the west since the 7th century and Turkic peoples after the Turkic migration from the north in the Middle Ages settled in the region. After Genghis Khan conquered Persia in the 13th century, many Mongols settled in Khorasan after depopulating its cities.
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historical region and realm comprising a vast territory now lying in northeastern Iran, southern Turkmenistan, and northern Afghanistan. The historical region extended, along the north, from the Amu Darya (Oxus River) westward to the Caspian Sea and, along the south, from the fringes of the central Iranian deserts eastward to the mountains of central Afghanistan. Arab geographers even spoke of its extending to the boundaries of India.
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