The first people to visit Alcatraz Island were native peoples who arrived between 10,000 and 20,000 years ago. Two major groups lived around the bay: the Miwok, who lived north of the bay in present-day Marin County, and the Ohlone, who lived in the coastal areas between Point Sur and the San Francisco Bay.
Early use of Alcatraz by these indigenous people is difficult to reconstruct, since most of the tribes’ oral histories have been lost. Historians believe that Alcatraz was used as a camping spot and an area for gathering foods, especially bird eggs and marine life. One tradition implies the island may have been used as a place of banishment for tribal members who violated tribal law.
By the time the first Spanish explorers arrived in 1769, more than 10,000 indigenous people lived around San Francisco Bay.
• On August 5, 1775, Spanish Lt. Juan Manuel de Ayala sailed his ship into San Francisco Bay and spent several weeks charting the harbor. During his surveys he described a rocky, barren island and named it “La Isla de Los Alcatraces” (Island of the Sea Birds). Historians debate which island Ayala actually sited, but the name eventually was given to the 22 acre rock today called Alcatraz.
• California became a possession of United States on February 2, 1848 in a treaty with Mexico that ended the Mexican War. A week earlier, on January 24th, gold had been discovered in the foothills of the Sierra Nevada Mountains. Within three years, the population of San Francisco would explode from around 500 to more than 35,000 as gold seekers poured into California.