In the mid-19th century, primarily in the 1860s, most of the Navajo were forced to abandon their homes due to a series of military campaigns by the U.S. Army at the orders of the U.S. government. The Army employed scorched earth tactics, burning the homes and farms of the Navajo, and stealing or killing livestock, to weaken and starve the Navajo into submission. In 1864, the main body of Navajo, numbering 8,000 adults and children, were marched 300 miles (500 km) on the Long Walk to imprisonment in Bosque Redondo. The Treaty of 1868 established the “Navajo Indian Reservation” and the Navajo people left Bosque Redondo for this territory.
The territory covered by the original grant of the reservation was bounded by a neat little quadrangle drawn on a map: the northern boundary was latitude 37° north, the western longitude 109°30′. In a decision most likely designed to keep the Navajo where they had been put, the other two boundaries were defined by lines running directly through two forts: Fort Defiance in the south (latitude 35°44′51″ north) and Fort Lyon in the east (longitude 103°07′57″ west). In practice, and particularly since no borders were marked or fences constructed, the Navajo frequently ignored these boundaries. The treaty under which the reservation was made specified an square 100 miles on a side; the actual territory was little more than half that area. Successive land grants would see the reservation grow, until today it is the largest in the United States.
