The point of divergence rests on the outcome of Admiral James Leyton's coup on Earth. In the Pendragon timeline, the coup was successful and triggered the start of a Federation Civil War which lasted until 2374.
Another key event that furthered the divergence between the timelines was the destruction of Deep Space 9 during the war, which sealed the Bajoran wormhole and prevented the Dominion War from beginning.
Events not stemming from the outcome of Leyton's coup, such as the second Borg incursion in 2373, occurred in the Pendragon timeline as in the mainstream universe, albeit sometimes with different outcomes.
This timeline was called the "Pendragon universe" because of the importance of the USS Pendragon in the years following the civil war.
The Department of Temporal Investigations eventually compared the events of the Federation Civil War to their database of other known timelines, and determined that while no temporal disruption was involved, a point in 2372 nonetheless marked a significant divergence from the majority of neighboring quantum realities in which there had been a Dominion War from 2373-2375, followed eventually by a Borg invasion in 2381. Those "prime events" ultimately resulted in greater devastation and loss of life than this timeline's Civil War and subsequent minor conflicts, leading some psychohistorians and temporal researchers of the 25th century to conclude that Admiral Leyton's actions may indeed have been justified. Further study indicated the effects of conservation of history at work as the timeline began to show greater synchronicity with the quantum meridian during the late 2370s and 2380s.