Gamma Delta is a planet whose inhabitants have been at war on and off for hundreds of years with the inhabitants of Gamma Origii. The origin of the conflict was that a d'clat (a canine-like animal) belonging to the emperor of Gamma Delta ate a markill (a feline-like animal) belonging to the empress of Gamma Origii. This incident led to bad feelings which eventually escalated to hostilities, but these origins have long since been forgotten by the inhabitants of the planet.
In an alternate timeline, in 2408 historical research done on Forever World led to the discovery of the origins of the conflict. When the inhabitants of the two planets learned of these origins, their leaders met and signed an agreement to leash d'clats and a newborn markill was presented to the leader of Gamma Origii. (TNG novel: Imzadi)