The Marasa Nebula was a chaotic cloud of highly energized gas which blocked hyperspace travel along the Trellen Trade Route. Since travel through the nebula was too hazardous to consider, starships traveling the route were forced to take a wide detour around the nebula during the days of the Galactic Republic. Unable to duplicate the Marasans' methods, the Empire elected to conquer the cyborg aliens, forcing them to guide their starships through the nebula.