Wikipedia
Al-Nasir li-Din Allah (6 August 1158 – 4 October 1225) was the 34th Abbasid Caliph in Baghdad from 1180 until his death. His laqab literally means The Victor for the Religion of God. He attempted to restore the caliphate to its ancient dominant role and achieved a surprising amount of success, despite the fact that the caliphate had long been militarily subordinated to other dynasties. He not only held Baghdad (the capital of the Abbasid empire), but extended his dominion into Mesopotamia and Persia. According to the historian, Angelika Hartmann, Al-Nasir was the last effective Abbassid Caliph.
Besides his occasional conquests, he consistently held Iraq from Tikrit to the Persian Gulf without interruption. His long reign of forty-seven years is chiefly marked by ambitious and corrupt dealings with the Tartar chiefs, and by his hazardous invocation of the Mongols, which so soon brought his own dynasty to an end. But in his day, there was comparative peace at Baghdad; learning flourished; while refuges for the poor, and other works of public interest, were encouraged.