The bigger the city, the more the loot.

The Mongols had to conquer vast areas of urban empires. Hundreds of towns and cities were in their way. In many of these cities were large amounts of gold and precious trade goods. When they had no siege engines the Mongols had to find other ways. One was to use prisoners. When one city was captured all the strong unskilled men were brought together. At the next city they would be driven forward in front of the main army to the gates. The defenders would sympathize with the prisoners and often opened the gates. Next thing they knew, masses of horses trampled them down. If a city resisted then many of the inhabitants would be slaughtered or turned into prisoners. Artisans and craftsmen would be sent back to Monolia to work there, more or less as slaves. There are many interesting stories related to these times. They involve frightened kings, valiant princes, and a shah who was running for his life. I'll tell them all later. Stay tuned.