Complex sentence: In actuality, most hits of the mid 1950s and early 1960s were written elsewhere, and the Brill Building's music was more sophisticated than other pop styles of the time, combining then-modern sounds with classic Tin Pan Alley songwriting.
Split into simpler sentences: In actuality, most hits of the mid 1950s and early 1960s were written elsewhere. The Brill Building's music was more sophisticated than other pop styles of the time, combining then-modern sounds with classic Tin Pan Alley songwriting.