The roots of American democracy derive, not from the Old World European precedents, but from the unique political structure of the American Indians. Early colonial settlers, coming from the monarchical and often tyrannical rule of European powers, knew little of democracy. Over time, as the colonies won their independence from England, a select group of representatives from each of the colonies gathered at the Constitutional Convention in Philadelphia, hoping to create a system in which there was a union of thirteen separate and sovereign states, similar to the political structure of the Iroquois. The Iroquois League of Nations, a union of five principal Indian nations, was studied by the great minds of the time including Benjamin Franklin, Thomas Paine, Charles Thompson, and Thomas Jefferson. Thus, many important aspects of the Constitution, such as republicanism, federalism, and popular sovereignty, can be closely associated with the system of the Iroquois League. The Founding Fathers also borrowed many distinctive qualities from the Iroquois such as the separation of civilian and military authority, the right to impeach, the caucus, expansion, electoral college, uninterrupted speech, and limited compensation for officials of the government. In the subsequent years after the ratification of the Constitution, the Indians continued to play a major role in the development of democracy because of their interactions with Americans on the frontier. These settlements produced such prominent figures as Henry Clay, Andrew Jackson, Davy Crockett, Abraham Lincloln, and Sam Houston, who was eventually adopted into the Cherokee nation. Most democratic reforms in the past two centuries, such as suffrage, senatorial elections, primary elections, and recalls, originated in the frontier settlements. Thus, it is necessary to ascribe the foundation and evolution of American democracy to the political structure of the American Indians.