Complex sentence: The Kansas City Monarchs were the longest running franchise in the Negro Leagues and were successful, winning eleven league championships before integration (1923--25,1929,1931 in the NNL; 1937--40,1942,1946 in the NAL).
Split into simpler sentences: The Kansas City Monarchs were the longest running franchise in the Negro Leagues. The Monarchs and were successful, winning eleven league championships before integration (1923--25,1929,1931 in the NNL; 1937--40,1942,1946 in the NAL).