Complex sentence: In the United States, the sheet music industry rose in tandem with blackface minstrelsy, and the group of New York City-based publishers and composers dominating the industry was known as "Tin Pan Alley".
Split into simpler sentences: In the United States, the sheet music industry rose in tandem with blackface minstrelsy. The group of New York City-based music publishers, songwriters and composers dominating the industry was known as "Tin Pan Alley".