Answer:
Kublai instituted a class system that placed Mongols on top, followed by Central Asians, Northern Chinese, and finally Southern Chinese. The latter two classes were more heavily taxed, especially to fund Kublai’s failed – and expensive – military campaigns.
These campaigns included attacks on Burma, Vietnam and Sakhalin, which successfully resulted in these regions becoming tributary states of the empire with tributes that were, unfortunately, dwarfed by the costs of the individual campaigns.
