Before Spanish colonization, Mexico has established its own class structure among the population. However, after colonization, the class structure changed drastically. The Spanish elites imposed a caste system with different levels of biological mixtures between different ethnic groups living in Mexico which decided one's status in society. Those who were biologically more Spanish enjoy a better standard of life than those from Indigenous or African lineage. The strict hierarchy caused discontent among the people which led to civil unrest and an inevitable revolution.