How did the Mongols learn to capture fortified cities?

The Mongols were originally a cavalry-based force suited for open plains, which meant they initially lacked the capability to capture fortified cities. Their ability to conduct successful sieges was a result of their remarkable adaptability and willingness to exploit new technological and human resources as they expanded their empire.123

To overcome the limitations of their traditional steppe warfare, the Mongols learned to capture fortified cities through the following methods:

• Recruitment of Experts: The Mongols frequently secured the assistance of artisans and engineers from technically advanced conquered peoples, including Chinese, Persians, and Arabs. These specialists provided the expertise needed to operate and construct siege equipment.14
• Adoption of Siege Technology: They incorporated sophisticated military engineering into their operations, utilizing tools such as mangonels, catapults, ladders, and incendiary devices.24
• Strategic Adaptation: Through contact with settled states, the Mongols learned the importance of towns and the value of utilizing peasants and craftsmen as producers of goods. They also employed tactics such as diverting rivers to breach defenses.2
• Forced Labor: In some campaigns, such as the war against the Khwārezmian Empire, the Mongols forced the inhabitants of captured cities to serve as advance troops or laborers against their own people.2