The position of the defensive fortifications of the cities of Transoxiana and Khorasan against the Mongols

The cities of Khorasan and Transoxiana on the time of the Mongol invasion (616 AH) under the leadership of Ghingiz Khan benefited from a series of defensive fortifications such as fortifications, Walls, Forts and Trench (Khandagh), whose main function was security and protection of the city against foreign threats. The existence of these structures confident Sultan Khwarezmshahs to base his battle strategy on defense in cities and castles in the initial decision. The present article, with a descriptive-analytical approach, considers the situation of these structures on the eve of the Mongol invasion and what effect they had on the method of battles between the Khwarezmshahs and the Mongols. According to the findings, on the time of the Mongol invasion, the defensive fortifications in most of the attacked cities were worn out and under repair. The deterrence and resistance of the defensive fortifications against the Mongol invasion is considered insignificant and the resistance in Otrar, Gurgandj (Urgench) Taleghan and Herat could not prevent the Mongol advance. The Mongols 'skill in besieging and capturing fortifications, the worn-out and under-repairing fortifications in some cities, and the lack of experienced and sufficient forces to maintain security structures are the most important causes of the fall of defensive fortifications against the Mongols' methods of warfare. After capturing the cities, the Mongols destroyed the defensive fortifications of Khorasan and Transoxiana in order to seize the opportunity to resist and revolt. Due to security concerns, Khorasan's defensive structures were not rebuilt from the center of the government and the conflict between Chagtai Khanate and the Ilkhans lasted until the end of the Ilkhanid period.