Sector 19 designated a specific area within the Trymant system. This star system was located in the Outer Rim Territories and also the Western Reaches, both of which are regions of the galaxy. During the period known as the High Republic Era, the Galactic Republic utilized a satellite, specifically the Republic Security Zone Monitoring Satellite 777B-Alpha, to keep watch over sector 19.
In the year 232 BBY, the Great Hyperspace Disaster resulted in events called Emergences. These involved debris from the destroyed Legacy Run freighter reverting from hyperspace back to realspace and subsequently colliding with planets and other celestial objects throughout the galaxy. At that time, a Dug worker stationed on the monitoring satellite was at their workstation, talking to themselves while observing that neither sector 17, sector 18, nor sector 19 presented anything noteworthy. However, the Dug's attention was quickly diverted when they noticed hyperspace debris entering the Trymant system near their location, and they informed their captain, who then gave the order to evacuate and also alerted the Starlight Beacon space station.
The first reference to Sector 19 occurred in the first issue of the 2021 comic series titled Star Wars: The High Republic Adventures, which was a part of Phase I of the larger Star Wars: The High Republic multimedia project. Daniel José Older was the writer of the issue, and it was published on February 3, 2021, by IDW Publishing. Prior to the release, on November 17, 2020, a preview featuring the mention of the sector was included in an article on StarWars.com that announced the comic series.