Notron
From Wookieepedia, the Star Wars wiki.
Notron was possibly the original Human homeworld, according to Seoularian legend.
By the time of the Galactic Civil War, Notron was a lost planet, and its location was unknown. Notron may even have been an ancient name for an already known planet. For example, it may have been the Seoulian name for Coruscant, since the Galactic capital was often considered Humanity's homeworld.
Presumably, Notron was in the Core Worlds.
