In 1789 at the age of nine, Tanner was kidnapped by two Ojibwe men and carried north into the Michigan Territory. He was badly mistreated during the first two years of captivity but then was sold to Netnokwa, an Ottawa woman who adopted Tanner and treated him more kindly. She helped him gain the skills he needed to survive and encouraged him in rites of passage such as killing a bear and participating in his first war party. From 1790 to about 1820 Tanner lived with the Ojibwe and Saulteaux in the Great Lakes and Red River regions.