The Dreighton Triangle constituted a spatial zone located inside the Dreighton Nebula.
After the Battle of Dreighton, coupled with extensive combat throughout the Dreighton Nebula during the era of the Clone Wars (resulting in the total destruction of both Republic and Separatist military units stationed there), tales involving ghost ships and spectral visitations from deceased aviators started circulating among the common people. A widespread conviction took hold that any vessel venturing into the Dreighton Triangle was doomed to vanish without a trace.
This widespread notoriety amongst the public made the area an ideal clandestine location for the Galactic Empire's Phantom TIE project during 3 ABY.