The earliest archaeological evidence of human settlements in the Bay Area dates back to 8000-10,000 BC ( ref . Coyote Hills Shell mound ) . In 1769 , the Bay Area was inhabited by the Ohlone people when a Spanish exploration party led by Gaspar de Portolà entered the Bay – the first documented European visit to the Bay Area . After Mexico established independence from Spain in 1821 , the region was briefly controlled by the Mexican government until the United States purchased the territory in 1846 during the Mexican – American War . Soon after , discovery of gold in California attracted a flood of treasure seekers , many using ports in the Bay Area as an entry point . During the early years of California 's statehood , state legislative business rotated between three locations in the Bay Area before a permanent state capital was established in Sacramento . A major earthquake leveled the city of San Francisco and environs in 1906 , but the region quickly rebuilt in time to host the 1915 Panama-Pacific Exposition . During World War II , the Bay Area played a major role in America 's war effort in the Asiatic-Pacific Theater , with San Francisco 's Fort Mason acting as a primary embarkation point for American forces . In 1945 , the United Nations Charter was signed in San Francisco , establishing the United Nations , and in 1951 , the Treaty of San Francisco officially ended the U.S. 's war with Japan . Since then , the Bay Area has experienced numerous political , cultural and artistic movements , developing unique local genres in music and art and establishing itself as a hotbed of progressive politics . Economically , the post-war Bay Area saw huge growth in the financial and technology industries , creating a vibrant and diverse economy with a gross domestic product of over $ 800 billion , and home to the second highest concentration of Fortune 500 companies in the United States
major earthquake
1906 San Francisco earthquake
San Francisco Bay Area