Entre Douro e Minho is one of the historical provinces of Portugal which encompassed the country's northern Atlantic seaboard between the Douro and Minho rivers. Contemporaries often referred to the province as simply "Minho". It was one of six provinces Portugal was commonly divided into since the early modern period until 1936, although these provinces were not recognized as official units of government.
Entre-Douro-e-Minho Province Wikipedia
Since the then separated municipalities of Gaia and Vila Nova were integrated in the administration of Porto city between 1383 and 1518, we can see some old maps showing areas south of the Douro River belonging to the old Entre-Douro-e-Minho territory, while other old maps make the province exactly match the current Viana do Castelo District, Braga District and Porto District.
Nevertheless if the name Entre-Douro-e-Minho ("Between-Douro-and-Minho") was strictly taken in account, the latter definition would make sense.
Then in 1936, when Portugal was divided into 13 official provinces, Entre Douro e Minho was split into Minho Province and Douro Litoral Province.
This reform would make Minho Province corresponding exactly to nowadays' Viana do Castelo District and Braga District. Minho provincial chieftaincy was attributed to the city of Braga.
On the other hand, Douro Litoral corresponded to nowadays' Porto District plus four municipalities of Aveiro District, and two of Viseu District to the then new Douro Litoral Province. Douro Litoral chieftaincy was attributed to the city of Porto
Being seen as a trace of Estado Novo policies, the territorial definitions of 1936, though having innocuous and non-political characters, were erased in 1976 soon after the Carnation Revolution. Nevertheless people still use the designations of 1936 on a daily basis because they more or less accurately correspond to the historical identity of the locals e.g.: "Minhotos", "Durienses", "Beirões", "Ribatejanos", etc., and many books and maps still show them.Porto
Penafiel (city since 1770)
Viana do Castelo (1848)