Complex sentence: When he left the South for Chicago in 1950, he worked as a dishwasher while living with an uncle, through whom he met many of Chicago's blues masters, including Otis Rush (also a left-handed guitaritst) and Magic Sam.
Split into simpler sentences: When he left the South for Chicago in 1950, he worked as a dishwasher while living with an uncle. Through his uncle he met many of Chicago's blues masters, including fellow left-handed guitarist Otis Rush and Magic Sam.