High Quality Content by WIKIPEDIA articles! Sonoma is a historically significant city in Sonoma Valley, Sonoma County, California, USA, surrounding its historic town plaza, a remnant of the town`s Mexican colonial past. It was the capital of the short-lived California Republic. Today, Sonoma is a center of the state`s wine industry for the Sonoma Valley AVA Appellation, as well as the home of the nationally recognized Sonoma International Film Festival. Sonoma`s population was 10,648 as of the 2010 census.