(The Seljuk Sultanate at its height (during the reign of Malik Shah, 1098) included most of modern Turkey, excepting the area on the European side of the Bosphorus, which was in Byzantine hands. It bordered on the Fatimid caliphate of Egypt to the south and from 1097-1099 it bordered on lands lost to the Crusaders. The empire included modern Armenia, and bordered on modern Georgia to the North. It also included modern Khazakstan and bordered on the Ghaznavid Emirate (Modern Afghanistan, Pakistan and Punjab) to the East. While the Arabian Penninsula was still under the control of Arab nomads, the territory of Oman, across the Persian Gulf was also a Seljuk province. Other Seljuk provinces include the Sultanate of Rum, which bordered on the Bosphorus, the Danishmend Emirate and the Great Seljuk Sultanate. The empire did not include Lesser Armenia.)

The Seljuk Sultanate was an ancient Turkish empire. Its first period of expansion began in 1038, when it invaded to neighbouring Ghaznavid Emirate (see above for location). Under Toghril Beg, the Seljuks occupied the western provinces of the emirate (1037-63). Then from (1054-55), the Sunni Seljuks invaded Baghdad at the request of the Abbasid caliph, driving out the Shi'ite Buwayhids. Under Alp Arslan (1072-92), successor to Beg, the Seljuks invaded Syria and inflicted a crushing defeat on the Byzantines at Manzikert. Arslan's successor, Malik Shah led the empire to its greatest height. Under his reign, Byzantine Anatolia and Fatimid Palestine were added to the empire.

After Shah's death, the empire enterfed a period of civil war and decline. By 1100, many Seljuk provinces had declared independence, such as Rum and Danshimend. Palestine was regained by the Fatimids of Egypt, only to fall to the Crusaders, along with many other former Seljuk lands.

The second period of Seljuk expansion was under Zangi (1127-46), the atabeg (governor) of Mosul. Under his reign, Northern Syria was united and Edessa was retaken from the Crusaders in 1144. Nur al-Din (1146-74) Zangi's heir and son, conquered the rest of Syria and completely crushed the Shi'ite Fatimids. However, Egypt was not to fall into Seljuk hands. Saladin, Kurdish governor of Egypt and one of the most famous personalities of the period, rebelled and created the Ayyubid dynasty in 1177. In 1250, only 73 years later, the Mamlukes, a group of Turkish slave soldiers, toppled the Ayyubids and remained in power until 1517. The former Seljuk province of Rum also regained power and defeated the Byzantines soundly at Myriocephalum in 1176.

In the East, the Abbasid caliphate profited from Turkish decline, and in 1156, enjoyed a revival. The caliphate itself only included Iraq, but the fact that the Sunni Seljuks gave great respect to the caliph meant that the Abbasids excercised great spiritual authority. Meanwhile, the shahdom of Khwarism, just south of the Aral Sea was gaining power. This barbaric state of affairs might have continued, had it not been for Genghis Khan, who in 1219 broke the power of the Khwarizms and invaded all of the former Seljuk Empire. Even the Seljuks of Rum, far to the West, became mere vassals to the huge Mongol Empire.In 1258, the Mongols accomplished what the Seljuks had not, destroying the Abbasid caliphate. Then, two years later, the Mongols invaded and won Syria from the Mamlukes. The Mamlukes recovered after defeating the Mongols at 'Ain Jalut a few months later, but until the death of Timur the Lame, originator of the Mughal Dynasty of India, the Mongols remained the largest political force.

Thrown into disarray by the Mongol invasion, the Sultanate of Rum collapsed. The Byzantines did not profit from this incredibly fortunate turn of affairs, as they had problems of their own. In fact, they were close to the end.

With the end of the Sultanate of Rum came the end of the Seljuk era. However, the stage was set for a new Turkish empire from Anatolia under the leadership of Osman I. The Ottoman age was about to begin.