Complex sentence: Rheingold shut down operations in 1976, when they were unable to compete with the large national breweries, as corporate consolidation and the rise of national breweries led to the demise of dozens of regional breweries.
Split into simpler sentences: Rheingold shut down operations in 1976, when they were unable to compete with the large national breweries. Corporate consolidation and the rise of national breweries led to the demise of dozens of regional breweries.