Sintheti was a planet-like astronomical object. It was located within the Sintheti system, which itself resided in the Noonian sector of the New Territories, a region found in the Outer Rim Territories. Its landscape was characterized by jagged, rocky formations known as crags.
Back in 402 BBY, individuals vying for control of Sintheti's Horned Throne separately engaged the services of the Mandalorian and Sun Guard mercenary groups. The ensuing conflict, known as the Battle of Sintheti, saw these two rival factions clashing for over three years amidst the planet's craggy terrain and within its underground catacombs.
Sintheti's existence was initially hinted at through the mention of the Battle of Sintheti in Galaxy at War, a 2009 sourcebook released by Wizards of the Coast for the Star Wars Roleplaying Game. The intention was to formally establish it as a distinct celestial body in The Essential Guide to Warfare, a 2012 reference book authored by Jason Fry and Paul R. Urquhart. However, the section containing Sintheti's description was ultimately removed prior to the book's publication.
This information about Sintheti eventually surfaced in 2013 as part of Star Wars: The Essential Guide to Warfare Author's Cut, a series of articles posted on the StarWars.com Blog by Fry and Erich Schoeneweiss, showcasing content that had been cut from The Essential Guide to Warfare. The Online Companion to The Essential Atlas, a 2009 reference book, pinpointed the Sintheti system, and consequently Sintheti, within grid square N-6.