
The history of California begins thousands of years ago and includes important events like the California Gold Rush; the opening of the Transcontinental Railroad; the 1906 San Francisco earthquake; the start of the American gay rights movement; and the Silicon Valley high-tech boom.
California was first a Spanish colony and then a part of Mexico. The United States began to control the area during the Mexican-American War. California became a U.S. state in 1850.
Hollywood and Yosemite National Park are in California. So are many historic sites, like 18th- to 19th century missions; Alcatraz Federal Prison; the Golden Gate Bridge; the first Chinatown in the country; and the Manzanar internment camp, where Japanese-Americans were interned during WWII.
Thousands of years ago, people from Asia crossed a land bridge over the Bering Strait and entered what is now Alaska. These migrants then spread out across North America, including to modern-day California.
When Europeans arrived in California, there were around 30,000 indigenous people in modern-day California. This was around 13% of the indigenous people in North America.

See the main article: California Gold Rush
During the California Gold Rush, around 300,000 people traveled to California after gold was found at Sutter's Sawmill. The Gold Rush lasted from 1848–1855, peaking in 1852.
While around $2 billion in gold was found during the Gold Rush, very few gold miners got rich.
The Gold Rush had major effects on California's history, economy, and population. It may have helped the California Republic become a state in 1850. People came from all over the world to look for gold. San Francisco became one of America's major cities, and California's population boomed.

During the 1840s and 1850s, over 250,000 emigrants traveled to California to seek their fortunes. They came from across America and from other countries. This was the greatest mass migration in American history.
The California Trail was about 2000 miles long, and it usually took 3 to 6 months to complete the journey. It follows the same route as the Oregon Trail until Idaho, where they split up. (After that, the Oregon Trail goes west, while the California Trail goes south.) After this point, conditions are very harsh: travelers have to cross a 40-mile desert and then climb over the Sierra Nevada mountains.
Emigrants traveled to California for many reasons: to seek their fortunes; to mine gold; to obtain good farmland in a warm climate; to fulfill the ideas of Manifest Destiny; to leave crowded, filthy cities (where diseases were common); and/or to go on adventures.
In the 19th century, government agents and private militias committed a genocide of the indigenous people in California. State authorities encouraged, tolerated, and committed these acts.

Between 9,492 and 16,094 indigenous people were killed during the genocide, and between 10,000 and 27,000 were kidnapped for forced labor. Additionally, hundreds (or perhaps thousands) of indigenous people starved or were worked to death.
The indigenous population also decreased dramatically because of disease, low birth rates, and starvation. Indigenous Californians were often raped and/or separated from their children. The state of California used its institutions (like its state legislature and court systems) to take away native people's land by favoring white settlers' rights over theirs.
Since the 2000s, most American academics and many activist organizations have used the word "genocide" to describe this period of time. In 2019, California's governor Gavin Newsom stated:
"It's called genocide. That's what it was, a genocide. No other way to describe it. And that's the way it needs to be described in the history books. And so I'm here to say the following: I'm sorry on behalf of the state of California [for the] violence, discrimination and exploitation [approved] by [the] state government throughout its history".