Complex sentence: The tribe was led from 1959 to 1990 by Roger Jourdain, a cousin of tribal archeologist Ginger Thompson, who became a rather well-known and respected leader due to his comments against the United States government and his pragmatic attitude.
Split into simpler sentences: The tribe was led from 1959 to 1990 by Roger Jourdain. Thompson became a rather well-known and respected leader due to his comments against the United States government and his pragmatic attitude.