Demarcated in 1756, the Douro wine region contains 40,000 hectares of vines in the valley carved by the Douro River between Spain and Porto. Divided into three sub zones; Baixo Corgo, Cima Corgo and Douro Superior. In the past, production in the Douro focused on port, however, the recent trend is favoring the red table wines. More than 90 grapes are permitted in the making of Douro table wines. Touriga Nacional and Tinta Roriz are considered the best grapes for red table wines. Malvasia, Fina and Viosinho are the preferred white wine grapes. The Douro generally has hot, dry summers and very cold winters.