vice-Sultan Baktmar was arrested a year later after being accused of plotting to overthrow an-Nasir and take the throne for himself. Baibars al-Dewadar became the new vice-Sultan. Because of his experience with the Emirs and their plots, an-Nasir Muhammad became very suspicious and very sensitive to criticism. He even exiled the Caliph to Qus in 1338. Crackdown on corruption Slowly but systematically an-Nasir increased his power as sultan and took revenge on the emirs who had mistreated him in the past and on the emirs who plotted against him after his return to Egypt. He abolished a few official positions, seized the wealth and property of corrupt officials, discharged the Oirat Mongols from royal service and annulled the exceptional taxes and surcharges (Mikoos) which were imposed on the common people by the authorities and which enriched officials and made the emirs more powerful. He employed Emir Ibn al-Waziri, a man who was known to be tough on corruption, as the head of Dar al-Adl (Court of Justice) and every Monday the Sultan would listen to complaints from the common people against the officials and the emirs. He prohibited his governors from executing or physically punishing convicts without his permission and he shut an infamous prison near the Citadel. In 1314 he abolished the post of vice-Sultan. In 1315 he carried out a land survey to re-establish the amount of the taxes which the land owners and the landlords had to pay to the state. Internal and external situations During the third reign of an-Nasir Muhammad, Egypt did not witness any major external threats as both the Crusaders and the Mongols had been weakened by losses in battle and their internal conflicts. However, Mongol ruler Oljeitu besieged Mamluk fortresses but withdrew due to deadly summer heat in 1312–1313. In 1314 the city of Malatya was captured by Tankiz, the deputy of an-Nasir in the Levant. Sis and other towns were raided by the an-Nasir's forces. Inside Egypt, there were a few disorders in Upper Egypt due to law breaking activities by Arab tribesmen which were easily subdued. In February 1321, there was a serious disturbance between the Egyptian Muslim and Christian communities which developed after a few Christian churches were destroyed simultaneously in various parts of Egypt. This was followed by a series of fires at mosques and other buildings in Cairo. A few Christians were arrested as a result of