The story of the intense rivalry between the San Francisco 49ers and the Dallas Cowboys that lasted through the entire 1980's and 1990's. The story of the intense rivalry between the San Francisco 49ers and the Dallas Cowboys that lasted through the entire 1980's and 1990's. The story of the intense rivalry between the San Francisco 49ers and the Dallas Cowboys that lasted through the entire 1980's and 1990's. The story of the intense rivalry between the San Francisco 49ers and the Dallas Cowboys that lasted through the entire 1980's and 1990's.