Before contact with Europeans, the natives of North America were divided into many different polities, from small bands of a few families to large empires. Modern anthropology assigns some larger divisions into various "culture areas", regions within which a particular set of cultural, political, subsistence and/or linguistic traits predominated. These pre-Columbian American culture areas may also roughly correspond to particular geographic and biological zones of the continent. During the thousands of years of native inhabitation on the continent, cultures changed and shifted. One of the oldest cultures yet found is that of the Clovis peoples. Upon the arrival of the Europeans in the "New World", Native American population declined substantially, primarily due to the introduction of Europ