The Sultanate of Rum, or Seljuk Sultanate of Rum, was a culturally Turco-Persian, Sunni Muslim state established over conquered Byzantine territories and peoples (Rum) of Anatolia by the Seljuk Turks following their entry into Anatolia after the Battle of Manzikert in 1071. The name Rum was a synonym for the medieval Roman Empire and its peoples, as it remains in modern Turkish. The name is derived from the Aramaic (romī) and Parthian (frwm) names for ancient Rome, which had reached these languages via the Greek Ῥωμαῖοι (Romaioi). The Seljuk Turks used the name to refer to Anatolia. The Sultanate of Rum is considered to be the beginning of Turkish history in Anatolia.
The Sultanate of Rum seceded from the Seljuk Empire under Suleiman ibn Qutalmish in 1077. It had its capital first at Nicaea and then at Iconium. 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. In the east, the sultanate reached Lake Van. Trade through Anatolia from Iran and Central Asia was developed by a system of caravanserai. Especially strong trade ties with the Genoese formed during this period. 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. For the remainder of the 13th century, the Seljuks acted as vassals of the Ilkhanate. Their power disintegrated during the second half of the 13th century. The last of the Seljuk vassal sultans of the Ilkhanate, Mesud II, was murdered in 1308. The dissolution of the Seljuk state left behind many small Anatolian beyliks (Turkish principalities), among them the Ottoman dynasty which eventually conquered the rest and reunited Anatolia to become the Ottoman Empire.
Since the 1030s, migratory Turkish groups in search of pastureland had penetrated Byzantine borders into Anatolia. In the 1070s, after the Battle of Manzikert, the Seljuk commander Suleiman ibn Qutulmish, a distant cousin of Alp Arslan and a former contender for the throne of the Seljuk Empire, came to power in western Anatolia. Between 1075 and 1081, he gained control of the Byzantine cities of Nicaea and briefly also Nicomedia. Around two years later, he established a Sultanate that, while nominally still a Byzantine vassal state, became increasingly independent after six to ten years. The Sultanate was officially recognized as a vassal state by the Seljuk ruler Malikshah in 1084, but as late as 1085, Suleiman was tasked by Byzantine emperor Alexios I Komnenos to reconquer Antioch and the former travelled there on a secret route, presumably guided by the Byzantines.
Suleiman tried unsuccessfully to conquer Aleppo in 1086 and died in the Battle of Ain Salm, either fighting his enemies or by suicide. In the aftermath, Suleiman's son Kilij Arslan I was imprisoned and a general of his, Abu'l-Qasim, took power in Nicaea. Following the death of sultan Malik Shah in 1092, Kilij Arslan was released and established himself in his father's territories between 1092 and 1094, possibly with the approval of Malik Shah's son and successor Berkyaruq.
Kilij Arslan, although victorious against the People's Crusade of 1096, was defeated by princely soldiers of the First Crusade and driven back into south-central Anatolia, where he set up his state with its capital in Konya. He defeated three Crusade contingents in the Crusade of 1101. In 1107, he ventured east and captured Mosul but died the same year fighting Malik Shah's son, Mehmed Tapar. He was the first Muslim commander against the crusades.
Meanwhile, another Rum Seljuk, Malik Shah (not to be confused with the Seljuk sultan of the same name), captured Konya. In 1116 Kilij Arslan's son, Mesud I, took the city with the help of the Danishmends. Upon Mesud's death in 1156, the sultanate controlled nearly all of central Anatolia.
The Second Crusade was announced by Pope Eugene III and was the first of the crusades to be led by European kings, namely Louis VII of France and Conrad III of Germany, with help from other European nobles. The armies of the two kings marched separately across Europe. After crossing Byzantine territory into Anatolia, both armies were separately defeated by the Seljuk Turks. The main Western Christian source, Odo of Deuil, and Syriac Christian sources claim that Byzantine Emperor Manuel I Komnenos secretly hindered the Crusaders' progress, particularly in Anatolia, where he is alleged to have deliberately ordered Turks to attack them. However, this alleged sabotage was likely fabricated by Odo, who saw the empire as an obstacle, and moreover Emperor Manuel had no political reason to do so. Louis and Conrad and the remnants of their armies reached Jerusalem and participated in 1148 in an ill-advised attack on Damascus, which ended in their retreat. In the end, the crusade in the east was a victory for the Muslims.
Mesud's son, Kilij Arslan II, is the first known Seljuk ruler who is known to have used the title of sultan and captured the remaining territories around Sivas and Malatya from the last of the Danishmends. At the Battle of Myriokephalon in 1176, Kilij Arslan II defeated a Byzantine army led by Manuel I Komnenos. 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. During the last years of Kilij Arslan II's reign, the sultanate experienced a civil war with Kaykhusraw I fighting to retain control and losing to his brother Suleiman II in 1196.
Following Kilij Arslan II's death, the sultanate was divided amongst his sons. Elbistan was given to Tughril ibn Kılıç Arslan II, but when Erzurum was taken from the Saltukids at the start of the 13th century, he was installed there. Tughril governed Erzurum from 1192 to 1221. During 1211–1212, he broke free from the Seljuk state. 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.
Suleiman II rallied his vassal emirs and marched against Georgia, with an army of 150,000–400,000 and encamped in the Basiani valley. Tamar of Georgia quickly marshaled an army throughout her possessions and put it under command of her consort, David Soslan. Georgian troops under Soslan made a sudden advance into Basiani and assailed the enemy's camp in 1203 or 1204. In a pitched battle, the Seljukid forces managed to roll back several attacks of the Georgians but were eventually overwhelmed and defeated. Loss of the sultan's banner to the Georgians resulted in a panic within the Seljuk ranks. Süleymanshah was wounded and withdrew to Erzurum. Both the Rum Seljuk and Georgian armies suffered heavy casualties, but coordinated flanking attacks won the battle for the Georgians.
Suleiman II died in 1204 and was succeeded by his son Kilij Arslan III, whose reign was unpopular. Kaykhusraw I seized Konya in 1205 reestablishing his reign. Under his rule and those of his two successors, Kaykaus I and Kayqubad I, Seljuk power in Anatolia reached its apogee. Kaykhusraw's most important achievement was the capture of the harbour of Attalia (Antalya) on the Mediterranean coast in 1207. His son Kaykaus captured Sinop and made the Empire of Trebizond his vassal in 1214. He also subjugated Cilician Armenia but in 1218 was forced to surrender Aleppo, acquired from al-Kamil. Ala Al-Din Kayqubad I continued to acquire lands along the Mediterranean coast from 1221 to 1225. In the 1220s, he sent an expeditionary force across the Black Sea to Crimea. In the east he defeated the Mengujekids and began to put pressure on the Artuqids.
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. After three years, when he had finally quelled the revolt, the Crimean foothold was lost and the state and the sultanate's army had weakened. It is in these conditions that he had to face a far more dangerous threat, that of the expanding Mongols. The forces of the Mongol Empire took Erzurum in 1242 and in 1243, the sultan was crushed by Baiju in the Battle of Köse Dağ (a mountain between the cities of Sivas and Erzincan), resulting in the Seljuk Turks being forced to swear allegiance to the Mongols and became their vassals. The sultan himself had fled to Antalya after the battle, where he died in 1246; his death started a period of tripartite, and then dual, rule that lasted until 1260.