Complex sentence: In the 1930s, the Bluebird label recorded mostly blues and jazz, much of which was brought to the label by talent scout and record producer Lester Melrose, who had a virtual monopoly on the Chicago blues market.
Split into simpler sentences: In the 1930s, the Bluebird label recorded mostly blues and jazz. Many artists were brought to the label by talent scout and record producer Lester Melrose, who had a virtual monopoly on the Chicago blues market.