Complex sentence: The early Grunge movement revolved around Seattle's independent record label "Sub Pop", but by the early 1990s its popularity had spread, with Grunge acts in California and other parts of the U.S. building strong followings and signing major record deals.
Split into simpler sentences: The early Grunge movement revolved around Seattle's independent record label "Sub Pop". By the early 1990's its popularity had spread, with Grunge acts in California and other parts of the U.S. building strong followings and signing major record deals.