Learn about the Temecula Wine History; its roots before becoming the stellar wine region of southern California and its humble beginnings of the 1850 s. Though Temecula (formerly Rancho California) is a relatively young community (incorporated in 1989), the region officially became an American viticulture area in 1984. Modern Temecula wine country sits east of the Rainbow Gap in Riverside County and the wine community has grown considerably since those humble beginnings.