Galactic Core

The galactic core is the central region of the Milky Way Galaxy. Anchored by a supermassive black hole, it is subject to intense radiation and increased risk of astronomical near-misses (resulting in climate change on the local planets) which makes life unlikely to prosper in the region. Despite these troubles for life, at least one advanced species has been discovered near the galactic core, the Cytherians. The core is surrounded by an immense energy field called The Great Barrier.

From Memory Alpha