- "A former commander in the Republic Regions security force, Tarkin was most recently the lieutenant governor of Eriadu. He now oversees the greater Seswenna sector with a special emphasis on emerging military technology."
- ―HoloNet News
The Greater Seswenna was originally a region of the Galactic Republic in the Outer Rim Territories, consisting of Seswenna sector and surrounding sectors. The Greater Seswenna has appeared by 57 BBY. It was the area patrolled by Ranulph Tarkin's Republic Outland Regions Security Force, that consisted of associated Planetary Security Forces of Seswenna and surrounding sectors.
The Greater Seswenna was later expanded to the Inner Rim, also known by this time as Sector 18, as he became the theaters of operations of the Republic 18th Sector Army during the Clone Wars. After the Declaration of a New Order, it was reorganized in an Imperial Priority Sector and placed under the rule of Grand Moff Wilhuff Tarkin.
- The Essential Atlas
- The Essential Guide to Warfare
- Star Wars: Imperial Handbook: A Commander's Guide