Complex sentence: In February 2010, The City Champs were asked to join The North Mississippi Allstars on a U.S. tour, during which the trio opened the shows and sat in with the band on their set.
Split into simpler sentences: In February 2010, The City Champs were asked to join The North Mississippi Allstars on a U.S. tour. During this tour the trio opened for the Allstars and sat in with the band on their set.