Pre-Columbian California was inhabited by numerous Indian tribes, most of them living by hunting and gathering. Their main foods were acorns, fish, and game. Among the major tribes were the Hupa, Mojave, Modoc, and Yuma. At the time of contact with the Spanish, there were at least 150,000 Indians in California.

Important dates in California
1542 Juan Rodriguez Cabrillo explored San Diego Bay.
1579 Francis Drake sailed along the coast and claimed California for England.
1602 Sebastian Vizcaino urged that Spain colonize California.
1769 Gaspar de Portola led a land expedition up the California coast. Junipero Serra established the first Franciscan mission in California, in what is now the city of San Diego.
1776 Spanish settlers from New Spain (Mexico) reached the site of what is now San Francisco.
1812 Russian fur traders built Fort Ross.
1822 California became part of Mexico, which had just won its independence from Spain in 1821.
1841 The Bidwell-Bartleson party became the first organized group of American settlers to travel to California by land.
1846 American rebels raised the "Bear Flag" of the California Republic over Sonoma. U.S. forces conquered California during the Mexican War (1846-1848).
1848 James W. Marshall discovered gold at Sutter's Mill. The discovery led to the California gold rush. The United States defeated Mexico in the Mexican War and acquired California in the Treaty of Guadalupe Hidalgo.
1850 California became the 31st state on September 9.
1880's A population boom occurred as a result of a railroad and real estate publicity campaign that brought thousands of people to California.
1906 An earthquake and fire destroyed much of San Francisco.
1915 Expositions were begun at San Diego and San Francisco to mark the opening of the Panama Canal.
1945 The United Nations Charter was adopted at the San Francisco Conference.
1963 California became the state with the largest population in the United States.
1978 California voters approved a $7-billion cutback in state property taxes.
1989 A strong earthquake struck the San Francisco-Oakland-San Jose area.
1994 A strong earthquake struck Los Angeles.
2003 Voters recalled Governor Gray Davis and elected motion-picture star Arnold Schwarzenegger to replace him.

After the Spanish conquered Mexico in the early 16th century, they searched for other areas rich in gold, sending several sea expeditions northward along the Pacific coast. The first of these to reach what is now California was led by Juan Rodríguez Cabrillo, who in 1542 sailed from Navidad, Mexico, up the coast of California. His expedition reached San Diego Bay and claimed the land for Spain.

In 1579 the English privateer Francis Drake, on a voyage around the world, landed near San Francisco Bay and claimed the land for England. The Spanish reaffirmed their own claim to California by further exploration. They were motivated in part by the need for a safe harbor for returning Manila galleons, as ships engaged in trade between Mexico and the Philippines were called. In 1595, Sebastián Rodríguez Cermeño landed at what is now called Drake's Bay. (The bay, a short distance north of San Francisco Bay, is probably the site of Drake's landing of 1579.) In 1602 Sebastián Vizcaíno landed at Monterey Bay.

Colonization did not begin until 1769, when an expedition under Caspar de Portolá and Franciscan Father Junípero Serra established presidios (military posts) and missions at San Diego and Monterey. After San Diego had been reached, Portolá led an overland expedition in search of Monterey Bay, but he failed to recognize it and continued on, discovering San Francisco Bay.

A total of 21 missions were eventually established, placed about every 30 miles (48 km) from San Diego to Sonoma. The missions were intended to convert and educate the Indians. The Indians were encouraged to live at the missions and give up their traditional ways. However, the missionaries often treated the Indians like slaves, and occasional revolts were ruthlessly quelled.

The first Spanish settlers arrived with Juan Bautista de Anza in 1776 and founded San Francisco. To encourage settlement, the Spanish government made land grants to the Californios, as the Spanish colonists were called. The Californios established ranchos, or cattle ranches, and the production of hides, meat, and tallow became the mainstays of colonial California's economy. Mexico, including California, gained independence from Spain during 1821-22.

In 1812, Russians engaged in fur trading established an outpost, Fort Ross, north of San Francisco. They left in 1841, when the otter and seal in the region had been almost exterminated. In 1826, Jedediah Smith, a fur trapper and explorer, became the first American to reach California overland from the east. He was soon followed by other fur trappers and by American settlers.