The defeat of Kosedag is the beginning point of the decline and the calamities in the history of Anatolian Seljuks. Pursuant to the death of Giyaseddin Keyhusrev II, the covetous statesmen were involved in a struggle with each other in the name of his three sons. Therefore, they provided a great opportunity for the invasion of Anatolia by the Mongolians and their demands for heavy taxes. Mu,'ineddin Suleyman Pervane held the domination of the situations and he undertook the state affairs in the name of Kilic Arslan IV (1257-1266) and Giyaseddin Keyhusrev III (1265-1282). Thus he partially provided a period of peace and stability until the year of 1261.
However, the Anatolian Turks were offended with the domination of the Mongolians and they tried to find a solution to escape from them. As a result, the sultan Baybars of the Egyptian Turks who had won a victory in Ayn Calut against the Mongolians in the year of 1261 was invited to Anatolia. Baybars who came to Kayseri in the year of 1276 was a light of hope against the Mongolians, but when he could not find any support, he did not stay in Anatolia for a long time and returned to Egypt. Therefore, the old conditions persevered in Anatolia.
Pursuant to the return of Baybars, Abaga Han penetrated into Anatolia and annihilated lots of people and executed Mu'ineddin Suleyman Pervane (1277). The Seljuk dynasty survived by name from that time on until the year of 1308, and the administration of the state was actually dominated by the Mongolian general governors and commanders. Seljuk State administration and army were dispersed. However, the developments in economical and cultural fields continued until the death of Mu'ineddin Suleyman Pervane. Therefore, the Turkish union that was undermined in Anatolia would be restored in the course of the Ottoman State.