 The area now called Four Corners was initially American Indian land and beginning in the 16th century it was claimed by Spain as part of New Spain.After Mexico gained independence from Spain in 1821, the area was governed by Mexico until being ceded to the United States by the Treaty of Guadalupe Hidalgo in 1848 following the United States' victory in the Mexican–American War.The first boundary which would become part of the monument was set as part of the Compromise of 1850, which created the New Mexico Territory and Utah Territory.