Oberbergische means Upper Bergian, meaning it is the part of the mediaeval county of Berg which is up river. The other part of the county, lower down the river Wupper was called Niederbergisch or Lower Berg.
The districts in North Rhine Westphalia were changed between 1969/75. That is when the district coulod its currect size.
The coat of arms is a joining of the heraldic signs of the territories the district belonged to. The red-white bar in the top symbolizes the County of Mark and the lion that of Berg. Homburg Castle (near Nümbrecht) was the seat of the Princes of Sayn-Wittgenstein-Berleburg.