A divided Islamic world offered feeble resistance to the Crusaders who consolidated their hold on the eastern Mediterranean and imposed their fiefdoms on the region. The Seljuks, preoccupied with defending their eastern flank against the Afghan Ghaznavids, had thinned out their western defenses. The pagan Turkish tribes across the Amu Darya on the northeastern frontiers were a constant menace....

The origins of the Ottoman Empire are to be found in a combination of Turkish asabiyah and the Islamic spirit of ghazza (meaning, struggle in the cause of God). Asabiyah, a term used by Ibn Khaldun to denote tribal cohesion, is the force that holds together tribes through bonds of blood, a characteristic found in abundance among peoples of the desert and the nomads of...