Tehama County is a county located in the northern part of the U.S. state of California. It is bisected by the Sacramento River. As of 2010 its population was 63,463, up from 56,039 as of 2000. The county seat is Red Bluff.
The county is named for the City of Tehama. The origin of the name is not known. Suggested possible roots are the Arabic word tehama ("hot low-lands"), the Spanish word tejamanil (shingle), or "high water" in the dialect of local Native Americans.
The first permanent settlers in the area that is now Tehama County were Robert Hasty Thomes, Albert Gallatin Toomes, William George Chard, and Job Francis Dye. The four men were each given land grants by the government of Mexico in 1844. Thomes received Rancho Saucos, Toomes received Rancho Rio de los Molinos, Chard received Rancho Las Flores, and Dye received Rancho Primer Cañon o Rio de Los Berrendos. Later in the same year Josiah Belden received Rancho Barranca Colorado.
Famous early figures include Kit Carson, who took part in a fight that gave name to Bloody Island and Battle Creek, Jedediah Smith, John Fremont, and William B. Ide, the first and only president of the California Republic.