the dão was first officially recognized as a "região demarcada" in 1908. in the 1940s, to improve the quality of the wine from the region and promote some sort of national identity, the government of prime minister antónio de oliveira salazar instituted new regulations establishing the mandatory use of co-operatives in the region. these co-operatives would have exclusive privilege to the grapes grown in the region and were charged with making the wine that would be sold to private merchants. despite its intent, the regulations had an adverse effect on the dão wine region by promoting stagnation due to lack of competition, with some co-operative firms releasing inferior quality wine and even practicing un-hygienic winemaking. in 1979, portugal's application to the european union prompted authorities to overturn these rules, as the eu discouraged monopolistic practices in the wine industry.