Nomadic pastoral societies differed from settled agricultural civilizations in that they had lower population densities, a more equitable and less stratified social class structure, and were often organized into clans or tribes. The Mongols were able to build a huge empire through conquest due to several factors: they had a highly mobile cavalry, they were skilled warriors, and they incorporated defeated peoples into their armies. The Yuan Dynasty established by the Mongols in China had a political structure similar to previous dynasties in that it had one ruler with the mandate of heaven, but differed through having non-Chinese and non-scholar-officials in power. The Mongols changed Chinese social structure by elevating the status of non-