The Vaskan sector was a region of space in the Delta Quadrant.
In 2374, the USS Voyager landed on a Y class planetoid in the Vaskan sector to replenish its deuterium supplies, where it encountered a bio-mimetic lifeform. (VOY: "Course: Oblivion")
Vaskan sector might be named for the homeworld of the Vaskans (and Kyrians), which was visited by Voyager in "Living Witness", shortly before the events of "Demon".