Complex sentence: From 1967 through 1989, the Grateful Dead, an American rock band, performed at the Convention Center 57 times, and would typically perform "runs" of shows in which the band would perform several shows over the course of three to four days.
Split into simpler sentences: From 1967 through 1989, the Grateful Dead, an American rock band, performed at the Convention Center 57 times. In the 80's they started performing "runs" of shows over the course of three to four days.