Because of the enrollment applications and the native American's association with a specific geographical location, often associated with the Catholic missions, the bands of natives became known as the "mission band" of people associated with a Spanish mission. Some bands also occupy trust lands—Indian Reservations—identified under the Mission Indian Agency. The Mission Indian Act of 1891 formed the administrative Bureau of Indian Affairs unit which governs San Diego County, Riverside County, San Bernardino County, and Santa Barbara County. There is one Chumash reservation in the last county, and more than thirty reservations in the others.