A venture was launched in 18 BBY by the Chiss Ascendancy, the nation of the Chiss sentient species, at the border of what the Chiss refer to as Lesser Space, which is their term for the area beyond the Unknown Regions. Senior Captain Mitth'raw'nuruodo (also known as "Thrawn") was dispatched by the Ascendancy's Defense Hierarchy Council aboard his Chiss heavy cruiser, the Springhawk, with the goal of pinpointing the location of the Grysk warlike species. This followed Thrawn's destruction of one of their fleet's. However, during his search at the edge of Lesser Space, Thrawn didn't discover any evidence of the Grysks. Instead, he encountered a group of Neimoidian refugees who gave him information about the end of the Clone Wars, a war between the Confederacy of Independent Systems and the Galactic Republic.
Furthermore, the Chiss was informed about the rise of the Galactic Empire. The refugees requested that he bring the Ascendancy's full force to Coruscant, the Empire's capital city, with the intention of destroying the Empire, kill Emperor Palpatine, and restoring the Republic. Subsequently, Thrawn returned to Csilla, the Ascendancy's capital planet, and later recounted the details of the mission to Admiral Ar'alani while explaining the reasons for exiled.
The 2017 novel Thrawn, which is the first book in the Star Wars: Thrawn novel series by Timothy Zahn, made an initial, though indirect, reference to this mission.