In addition to Judeo-Christian Principles and Ancient Greek Philosophy, the American Founding father took inspiration from the Ancient Romans who formed the first Republic in history.
Most agree that the Roman Republic was formed around 509 BC after the end of the Roman Empire. However, the Republic was not a democracy. Practically, it was more of an oligarchy where a small number of families had voting rights.
However, it was one of the first times when the power of a 'King' or an 'Emperor' was restricted. This idea of a ruler not having unlimited power was very crucial to the American founding fathers.
