Sonoma Valley is a valley located in southeastern Sonoma County, California, in the North Bay region of the San Francisco Bay Area. Known as the birthplace of the California wine industry, the valley is home to some of the earliest vineyards and wineries in the state, some of which survived the phylloxera epidemic of the 1870s and the impact of prohibition in …Sonoma Valley is a valley located in southeastern Sonoma County, California, in the North Bay region of the San Francisco Bay Area. Known as the birthplace of the California wine industry, the valley is home to some of the earliest vineyards and wineries in the state, some of which survived the phylloxera epidemic of the 1870s and the impact of prohibition in the early 20th century. Today, the valley's wines are promoted by the U.S. federal government's Sonoma Valley and Carneros AVAs.