Complex sentence: CMT Music (formerly CMT Pure Country) is a digital cable television channel which is the sister network to CMT that is run as part of the Viacom Music and Entertainment Group, a unit of the Viacom Media Networks division of Viacom.
Split into simpler sentences: CMT Music (formerly CMT Pure Country) is a digital cable television channel and a sister network to CMT. It is part of the Viacom Music and Entertainment Group, a unit of the Viacom Media Networks division of Viacom.