Feudalism

Almost all countries on the Continent operate on a feudalistic basis. Under feudalism, the power and authority is in the hands of one individual at the top, who personally owns a large portion of the land that the they oversee. These rulers are most called kings (or queens). Kings have vassals that swear fealty to them and in exchange benefit from royal protection and the right to govern a smaller portion of the kingdom. These vassals are powerful nobles who own large swathes of land and collect taxes from them. These nobles then pay some portion of their income to their lord. Nobles and royals use these funds to buy expensive equipment for themselves and their soldiers so they can protect those under their rule. 

A shift to a system of feudalism began during the Mountain War, where the dwarves rulers were overthrown and went into hiding. As the dwarves have a longer lifespan than humans, their warriors were better trained and better equipped than the human conscripts that were used against them. As the style of warfare began to shift towards cavalry, which could easily outmaneuver the slow dwarf heavy infantry, human armies began favoring better armed warriors who could afford things such as heavy armor and horses. After the war was won, dwarven raids became more common, which also required a swift and decisive response, which neccessitated heavy cavalry. With this shift, the need for a new class was born. A class that could spend their days training to become warriors and help those in their protection. While the dwarf threat became a thing of the past, continental society embraced its results and with the ever increasing frequency of holy wars, the societal order doesn't seem to change any time soon.