Alta California, also known as Nueva California, among other names, was a province of New Spain, formally established in 1804. Along with the Baja California peninsula, it had previously comprised the province of Las Californias, but was split off into a separate province in 1804. Following the Mexican War of Independence, it became a territory of Mexico in April 1822 and was renamed Alta California in 1824. The territory included all of the modern U.S. states of California, Nevada, and Utah, and parts of Arizona, Wyoming, Colorado, and New Mexico. In the 1836 Siete Leyes government reorganization, the two Californias were once again combined. That change was undone in 1846, but rendered moot by the U.S. military occupation of California in the Mexican-American War.
Neither Spain nor Mexico ever colonized the area beyond the southern and central coastal areas of present-day California and small areas of present-day Arizona, so they exerted no effective control in modern-day California north of the Sonoma area, or east of the California Coast Ranges.