It reached the height of its power during the late 12th and early 13th century, when it succeeded in taking key Byzantine ports on the Mediterranean and Black Sea coasts.

The increased wealth allowed the sultanate to absorb other Turkish states that had been established following the conquest of Byzantine Anatolia: Danishmendids, House of Mengüjek, Saltukids, Artuqids.

The Seljuk sultans bore the brunt of the Crusades and eventually succumbed to the Mongol invasion at the 1243 Battle of Köse Dağ.

In 1107, he ventured east and captured Mosul but died the same year fighting Malik Shah's son, Mehmed Tapar.

However, this alleged sabotage of the Crusade by the Byzantines was likely fabricated by Odo, who saw the Empire as an obstacle, and moreover Emperor Manuel had no political reason to do so.

Mesud's son, Kilij Arslan II, is the first known Seljuk ruler who is known to have used the title of sultan[21] and captured the remaining territories around Sivas and Malatya from the last of the Danishmends.

Despite a temporary occupation of Konya in 1190 by the Holy Roman Empire's forces of the Third Crusade, the sultanate was quick to recover and consolidate its power.

[25] In 1230, Jahan Shah bin Tughril who was allied to the Khwarazmshah Jalal al-Din, lost the Battle of Yassıçemen, allowing for Erzurum to be annexed by the Seljuk sultanate.

In a pitched battle, the Seljukid forces managed to roll back several attacks of the Georgians but were eventually overwhelmed and defeated.

[citation needed] Kaykhusraw II (1237–1246) began his reign by capturing the region around Diyarbakır, but in 1239 he had to face an uprising led by a popular preacher named Baba Ishak.

His younger brothers, Kilij Arslan IV (1248–1265) and Kayqubad II (1249–1257), were set to rule the regions east of the river under Mongol administration.

Kilij Arslan IV was executed in 1265, and Kaykhusraw III (1265–1284) became the nominal ruler of all of Anatolia, with the tangible power exercised either by the Mongols or the sultan's influential regents.

But since the native forces who had called him to Anatolia did not manifest themselves for the defense of the land, he had to return to his home base in Egypt, and the Mongol administration was re-assumed, officially and severely.

Also, the Armenian Kingdom of Cilicia captured the Mediterranean coast from Selinos to Seleucia, as well as the cities of Marash and Behisni, from the Seljuk in the 1240s.

A distant relative to the Seljuk dynasty momentarily installed himself as emir of Konya, but he was defeated and his lands conquered by the Karamanids in 1328.

The sultanate's monetary sphere of influence lasted slightly longer and coins of Seljuk mint, generally considered to be of reliable value, continued to be used throughout the 14th century, once again, including by the Ottomans.

[63] In the 13th century, most Muslim inhabitants in major Anatolian urban hubs reportedly spoke Persian as their main language.

[67] The notable historian Ibn Bibi composed a six-volume Persian language poetic work called the Selçukname, modeled after the Shahnamah, which focused on the Seljuk sultans.

[69] The Rahat al-sudur, the history of the Great Seljuk Empire and its breakup, written in Persian by Muhammad bin Ali Rawandi, was dedicated to Sultan Kaykhusraw I.

[76] With a population that included Byzantine Greeks, Armenians, Kurds, Turks, and Persians, the Seljuks were very successful between 1220 and 1250 and set the groundwork for later Islamization of Anatolia.

[78] Among these, the caravanserais (or hans), used as stops, trading posts and defense for caravans, and of which about a hundred structures were built during the Anatolian Seljuk period, are particularly remarkable.

[81] The largest caravanserai is the Sultan Han (built-in 1229) on the road between the cities of Konya and Aksaray, in the township of Sultanhanı, covering 3,900 m2 (42,000 sq ft).

[citation needed] The Seljuk palaces, as well as their armies, were staffed with ghilmān (Arabic: غِلْمَان), singular ghulam), slave-soldiers taken as children from non-Muslim communities, mainly Greeks from former Byzantine territories.

[82] The earliest documented Rum Seljuq copper coins were made in the first part of the twelfth century in Konya and the eastern Anatolian emirates.

[83] Extensive numismatic evidence suggests that, starting in the middle of the thirteenth century and continuing until the end of the Seljuk dynasty, silver-producing mints and silver coinage flourished, particularly in central and eastern Anatolia.

[84] Most of Kilij Arslan II's coins were minted in Konya between 1177–78 and 1195, with a small amount also occurring in Sivas, which the Rum Seljuks conquered from the Danishmendids.

Muhyiddin Mesut, son of Kilij Arslan II, minted coins in the northwesterly cities of Ankara, Çankırı, Eskişehir, and Kaztamunu from 1186 to 1200.

[85] The image of a horseman with two more arrows ready and his bow taut represents strength and control and is a representation of the ideal Seljuq king of the Great Age.

[87] The Seljuq silver coinage's superior quality and prominence contributed to the dynasty's affluence throughout the early part of the thirteenth century and explains why it served as a kind of anchor for the local "currency community.