The Great Imperial Split

The death of Emperor Palpatine at the Battle of Endor marked the end for his Empire. The Galactic Empire was far too large to be destroyed in one blow, however, and so, there having been no contingency plan in place for Palpatine's death, the Galactic Empire split into hundreds of smaller factions.

Any sense of order and stability in the galaxy disappeared practically overnight as the Empire fractured. The galaxy was in a state of total war for a four-year long period from 4 ABY to 8 ABY, with entire planets being obliterated by massive fleets and Imperial infighting. It was as if the whole galaxy was on fire. The Imperial split was a conflict far greater and more damaging than even the Clone Wars.

The situation was eventually stabilized by the time of 8 ABY with the Thrawn's Hand, the Pentastar Alignment, and the New Republic taking control of the majority of the Galactic Empire's former territory between the three of them, though not all of it. Some minor factions still managed to hold on to their own territory.