In 2000, CBS came under the control of the original incarnation of Viacom, which was formed as a spin-off of CBS in 1971. In 2005, Viacom split itself into two separate companies and re-established CBS Corporation through the spin-off of its broadcast television, radio and select cable television and non-broadcasting assets, with the CBS network at its core.[4][5][6] CBS Corporation was controlled by Sumner Redstone through National Amusements, which also controlled the second incarnation of Viacom until December 4, 2019, when the two separated companies agreed to re-merge to become ViacomCBS. Following the sale, CBS and its other broadcasting and entertainment assets were reorganized into a new division, CBS Entertainment Group.