Genetic evidence suggests at least three waves of migrants arrived from Asia, with the first occurring at least 15 thousand years ago.These early inhabitants, called Paleoamericans, soon diversified into many hundreds of culturally distinct nations and tribes.Artifacts from this culture were first excavated in 1932 near Clovis, New Mexico.The Clovis culture ranged over much of North America and also appeared in South America.It is not definitively known how or when the Native Americans first settled the Americas and the present-day United States.The prevailing theory proposes that people migrated from Eurasia across Beringia, a land bridge that connected Siberia to present-day Alaska during the Ice Age, and then spread southward throughout the Americas over the subsequent generations.The term excludes Native Hawaiians and some Alaska Natives.The ancestors of modern Native Americans arrived in what is now the United States at least 15,000 years ago, possibly much earlier, from Asia via Beringia.
These were complex nomadic cultures based on (introduced) horse culture and seasonal bison hunting. Cultural activism since the late 1960s has increased political participation and led to an expansion of efforts to teach and preserve indigenous languages for younger generations and to establish a greater cultural infrastructure: Native Americans have founded independent newspapers and online media, recently including First Nations Experience, the first Native American television channel; established Native American studies programs, tribal schools, and universities, and museums and language programs; and have increasingly been published as authors in numerous genres.
After the thirteen colonies revolted against Great Britain and established the United States, President George Washington and Henry Knox conceived of the idea of "civilizing" Native Americans in preparation for assimilation as U. During the 19th century, the ideology of manifest destiny became integral to the American nationalist movement. Congress passed the Indian Removal Act, authorizing the government to relocate Native Americans from their homelands within established states to lands west of the Mississippi River, accommodating European-American expansion.
Expansion of European-American populations to the west after the American Revolution resulted in increasing pressure on Native American lands, warfare between the groups, and rising tensions. This resulted in the ethnic cleansing of many tribes, with the brutal, forced marches coming to be known as The Trail of Tears.
Europeans at that time had patriarchal cultures and had developed concepts of individual property rights with respect to land that were extremely different.
The differences in cultures between the established Native Americans and immigrant Europeans, as well as shifting alliances among different nations in times of war, caused extensive political tension, ethnic violence, and social disruption.