Patricians are wealthy landowners, which mostly got government positions, Plebeians are normal citizen which got no government positions but are allowed to vote. After Rome conquer more and more territory, more "trophies" start to appear, such as slaves, the wealthy people (Patricians) can afford slaves, but the Plebeians can not, slaves can grow more crops, which cause the Plebeians to lose their competitive advantage, this made the relationship between the two social class tenser.