Tlön was a homeworld to the sentient Tlönian species of arachnoid beings. This world existed within the Tlönia system, which itself was situated in the Demetras sector. The sector was located in the Trans-Hydian portion of the Outer Rim Territories. These Tlönians were known to attack starships that dared to travel beyond the Galactic Republic's frontier.
The Mandalorian Crusader warrior culture, sometime after the 6700s BBY, turned their attention to the Tlönians. According to the Ba'jurne Kyr'tsad Mando'ad, a text attributed to Tor Vizsla, a later Mandalorian, the Crusaders considered them "unworthy and unclean." By the time of the 6100s BBY, Tlön had been incinerated and its population wiped out. Vilnau Teupt mentioned this event in "Industry, Honor, Savagery: Shaping the Mandalorian Soul," his keynote address at the 412th Proceedings of Galactic Anthropology and History held by Brentaal Academy in 24 ABY. Ultimately, the Tlönian species was completely rendered extinct.
The Essential Guide to Warfare, a 2012 reference book by Jason Fry and Paul R. Urquhart, included a mention of Tlön. The 2009 reference book The Essential Atlas placed the Tlönia system, and consequently Tlön, within grid square P-7.