How did the Mongols capture heavily defended walled cities?

The Mongols initially relied on highly mobile cavalry suited for open plains, which were ineffective against fortified cities. To overcome this, they adapted by integrating advanced military engineering and technology from conquered peoples, particularly Chinese, Persian, and Arab artisans and engineers.123

Their siege tactics included:

• Siege Engines: They utilized catapults, mangonels, and trebuchets to damage fortifications.243
• Engineering Feats: They employed ladders for scaling walls and even diverted rivers to compromise city defenses.2
• Incendiary Devices: They made extensive use of fire and early incendiary weapons, potentially including early forms of gunpowder.23
• Psychological and Human Tactics: The Mongols frequently used propaganda and offered peace in exchange for voluntary surrender. When cities resisted, they often massacred the inhabitants or forced survivors to serve as advance troops against their own people, using terror as a strategic tool.12

By incorporating these sophisticated methods, the Mongols transformed from a nomadic force into a power capable of systematic urban conquest.2