The process of dissolution and fall of the Anatolian Seljuk Sultanate has begun during the short reign of Sultan Giyath al-Din Kay Khusraw II. Three major historical events affecting the domestic and foreign policies of the sultanate have played the main role in the begin-ning of this process. The first event has been the statesman Saad al-Din Kopek's attempt of seizing Seljuk political power. The second event has been the rebellion of popular sage Baba Ilyas of Khorasan who incited the Turkmens into revolt in order to end the Seljuk dynasty and replace it with himself. The third event has been the Battle of Kosedag (1243) that has changed the continuum of Turkish history and defined the fate of the Anatolian Seljuk Sultanate. As is known, this battle has been fought to stop the Mongol invasion of Anatolia. However, this battle has resulted with the total defeat of the Seljuk vanguard facing the Mongols and the disgraceful flight of both the Seljuk commanding staff including Sultan Kay Khusraw himself and the entire main body of the Seljuk army without engaging in combat. The price of this flight has been the invasion of Anatolia by the Mongols and the coming of the Anatolian Seljuk Sultanate under Mongol dominance, from which the sultanate would never be able to free itself ever again. In this article, we have tried to study and evaluate this historical event in regard to it's affect on Turkish history.