Rey's Nebula was a cloud of interstellar matter located along the the Corellian Trade Spine. The nebula was named after Corellia's first king, Rey Solo. Volo Asiago and Errol Dunewell used it as a point of reference to plot a jump toward King's Belt, the last known location of the Corellian Trade Spine.
Behind the scenes
Rey's Nebula was created by I'm the Chosen One. Rey is Spanish for "King". The size and appearance of the nebula is based on the Horseshoe Nebula which happened to be the original name of Rey's Nebula.