Ommol was a planet in the Unknown Regions, the homeworld of the Umdals. Heavily colonized by citizens and subjects of the Tetrarchy of Mezlagob, it became one of the Tetrarchy's forty-nine "prime worlds" and a crucial manufacturer of military technology, most notably the fearsome shock tanks that made up the backbone of the Tetrarchy's ground assault forces. The site of a lightning raid at the height of the Great Liberation, Ommol was captured by the Golden Empire after the the surrender of Mezlagob and became a member system of the new government.