The Foundation of the Ottoman Empire

At the end of the thirteenth century, Asia Minor, so long the battleground between the Khalifs and the Byzantines, almost entirely abandoned by the latter for a brief time to the Seljuk emperors of Rum, who had their seat at Konia, then again disturbed by the invasion of the Crusaders from the west and the Mongols from the east, was left to itself. The Byzantines, despite (or perhaps because of !) their re-establishment at Constantinople, were too weak to make any serious attempt to recover what they had lost to the Seljuk Turks.
The Mongols of the horde of Djenghiz Khan had destroyed the independence of the Sultanate of Konia, and had established their authority in that city. But they made no real effort to bring under their dominion the districts north-west and west of Konia to which they had logically fallen heir...