Ribera del Duero, important wine zone in castilla y león in north-central Spain that challenged rioja as the leading red wine-producing region in Iberia towards the end of the 20th century when it grew substantially. By 2012 it had a total of 21,500 ha/51,500 acres of vineyard, a third as much as Rioja. Ribera del Duero spans the upper valley of the River Duero (known as douro in Portugal), starting some 30 km/18 miles east of the city of Valladolid (see map under spain). Although Bodegas vega sicilia on the western margin of the denomination has been producing one of Spain’s finest wines since the mid 19th century, the region was awarded do status only in 1982. Since then more than 200 private estates have emerged.