Timelines A, B: The 1973 Split
Bolivar Trask, the head of Trask Industries, develops the Sentinel Program—and offers it to the U.S. government as a way to find and subdue the mutant populace. Raven, now operating under the alias Mystique, assassinates Trask, branching the timelines into Timeline A, the continuity of the original X-Men movies, and Timeline B, the timeline of the prequel-era reboot. We’ll get back to Timeline B eventually. (X-Men: Days of Future Past)
