Several ancient Greek, Roman, English, and Enlightenment influences shaped early American political thought. In ancient Greece, Athenian democracy allowed all citizens to debate and vote, though citizenship excluded many groups. Rome established representative government with its Senate and assemblies. England's Magna Carta, Petition of Right, and Bill of Rights protected rights and limited royal power. Enlightenment thinkers like Hobbes, Locke, and Montesquieu advocated natural rights, social contracts, separated powers, and limited government. The American colonies experimented with different forms of self-government under royal, proprietary, and charter systems.