Nekrit Expanse
The Nekrit Expanse is a nebular region in the Delta Quadrant that provides a natural barrier between the advanced species (such as the Borg, the Devore, etc.) who occupy space closer to the Galactic Core and the resource-poor, technologically-inferior species closer to the rim (the Kazon, Vidiians, etc.). This area of space is largely uncharted because of the navigational challenge it poses even to advanced vessels. This area of space is on the extreme edge of Borg space (including the entrance to the so-called Northwest Passage) and is sparsely populated.
Starfleet's interest in this area predominantly has to do with the fact that it has been completely ignored by most of the native powers, and so they would like to investigate what potential resources or worlds have gone unnoticed within its borders.