The colonization of the North American continent and its Native American population has been the source of legal battles since the early 19th century. Many Native American tribes were resettled onto separate tracts of land (reservations), which have retained a certain degree of autonomy within the United States. The federal government recognizes Tribal Sovereignty and has established a number of laws attempting to clarify the relationship among the federal, state, and tribal governments. The Constitution and later federal laws recognize the local sovereignty of tribal nations, but do not recognize full sovereignty equivalent to that of foreign nations, hence the term "domestic dependent nations" to qualify the federally recognized tribes.