Wealth in agrarian societies is tied to land, and medieval Japan was no different. In fact, land was the main reason for much of the discontent among the warrior class. Since the rise of the warriors under the Minamoto, it was expected that victory in battle would be rewarded by land grants given to those who served on the victorious side. However, unlike any war that had been fought until then, the Mongol invasions presented a problem since this war, which was seen by most Japanese as a patriotic duty, did not take place against another warrior family, but against a foreign enemy. After the foreign enemy's defeat there were no lands to hand out to the victors. This was especially a problem for those warriors who had fought valiantly and petitioned the Hōjō regents for land. Even in the beginning of the fourteenth century this discontent put a tremendous pressure on any regime that emerged. They had to immediately satisfy this group in order to succeed.