Sector 17 was a specific area within the Trymant system. The Trymant system itself was a star system located in both the Outer Rim Territories and the Western Reaches of the galaxy. During the High Republic Era, the Galactic Republic used a satellite, specifically Republic Security Zone Monitoring Satellite 777B-Alpha, to keep watch over sector 17.
In the year 232 BBY, the Great Hyperspace Disaster resulted in Emergences. These Emergences were caused when debris from the destroyed Legacy Run freighter suddenly reverted from hyperspace back to realspace and subsequently collided with various celestial objects throughout the galaxy. At the time, a Dug worker stationed on the monitoring satellite was at their workstation, idly commenting to themselves that nothing of interest was happening in sector 17, sector 18, or sector 19. However, the Dug's attention was quickly diverted by the appearance of hyperspace debris entering the Trymant system nearby. They then informed their captain, who ordered an immediate evacuation and alerted the Starlight Beacon space station.
The initial reference to Sector 17 occurred in the first issue of the 2021 comic series titled Star Wars: The High Republic Adventures. This comic was released as part of Phase I of the larger Star Wars: The High Republic multimedia project. Daniel José Older wrote the issue, and IDW Publishing published it on February 3, 2021. Prior to the release, on November 17, 2020, a preview featured in a StarWars.com article announcing the comic series included the initial mention of the sector.