What event marked the end of Native Americans traveling outside of Indian territory as well as the end of the plains wars?

It was Wounded Knee that marked the end of the Plains Wars and the end of resistance to the reservation and assimilation programs that were being instituted by the United States government.

Explanation:

Wounded Knee took place on December 29, 1890. During this event, the United States Army slaughtered up to an estimated 300 Lakota Indians near Wounded Knee Creek in southwestern South Dakota. The massacre is considered the pinnacle of efforts to repress the Plains Indians. It effectively ended organized attempts to resist being resettled into reservations and being assimilated by the mainstream culture. The United States government kept back-stepping and allowing interests to violate the treaties signed with the Plains Indians like The Treaty of Fort Laramie that was signed in 1868 and established a 60-million-acre Great Sioux Reservation. By 1877 it was only 21.7-million acres despite the agreements and it shrank further in 1887 with the General Allotment Act.