Complex sentence: He became interested in music as a child, and taught himself to play harmonica at an early age, and from the early 1940s was working as an itinerant musician in Tennessee, Missouri, Indiana, and Illinois.
Split into simpler sentences: He became interested in music as a child and taught himself to play the harmonica at an early age. Beginning in the early 1940s, he worked as an itinerant musician in Tennessee, Missouri, Indiana, and Illinois.