Closer to being a subsector in size than a true sector, the "Black Sector" is a roughly spherical region of space measuring approximately 46 parsecs in diameter, located in the center of the Great Reft (Reft Sector).  It is an area of space in which the normal rules hysperspace navigation do not seem to apply.

    The Great Reft itself represents a formidable navigation problem, due to the low density of planetary systems for fueling stops.  It's claw-shaped form separates the old Empires from it's neighbors, including the Aslan Hierate and the Vargr Extents.  Jumping across the Reft requires a ship capable of Jump-5, or capable of multiple smaller jumps without refueling.
But because of the strange properties of the Black Sector, it is an even more difficult challenge to navigate safely; few have entered the area and returned to tell about it.  Those who have ventured into it's outer fringes have reported a complete lack of navigational bearing once in the region.  Those who have escaped have done so by sheer luck, randomly picking coordinates for a jump that managed to lead them safely out.
    Perhaps the most intriuging fact about the Black Sector is it's reportedly young age.  The exact date of it's appearance is unknown, since the region it occupies is seldom travelled, but varying reports put it sometime within the year 2980.

    The area was once the topic of intense study by scientific institutes of the Empire, but most of the records of these studies were lost or unaccounted for after the war.  Today, it continues to be a topic of study, but expenditures on purely scientific pursuits by the Republic are but a tiny fraction of the former Empire's budget.  Still, the day may come when the mysteries of the Black Sector are revealed.