Gallatin was deeply interested in Native Americans, and he favored their assimilation into European-American culture as an alternative to forced relocation. He drew upon government contacts to research Native Americans, gathering information through Lewis Cass, explorer William Clark, and Thomas McKenney of the Bureau of Indian Affairs. Gallatin developed a personal relationship with Cherokee tribal leader John Ridge, who provided him with information on the vocabulary and the structure of the Cherokee language. Gallatin's research resulted in two published works: "A Table of Indian Languages of the United States" (1826) and "Synopsis of the Indian Tribes of North America" (1836). His research led him to conclude that the natives of North and South America were linguistically and culturally related and that their common ancestors had migrated from Asia in prehistoric times. Later research efforts include examination of selected Pueblo societies, the Akimel O'odham (Pima) peoples, and the Maricopa of the Southwest. In 1843, he co-founded the American Ethnological Society, serving as the society's first president. Due to his studies of the languages of the Native Americans, he has been called "the father of American ethnology."