Originally, this area was unclaimed for a large part of galactic history. When the nobles from the adjectant Senex-Juvex felt threatened by the approaching Republic and the forces of Eriadu, they claimed a number of rimward systems around 700 BBY. They became known as the Ninth Quadrant, a reference to the early days of the Senex-Juvex worlds, which had been divided into eight quadrants.
In the century following the Third Nantama Synod in 553 BBY, the Senex-Juvex were forced to hand the area over to the Republic and it became a part of the Outer Rim's Bozhnee sector. Among spacers, the name "Ninth Quadrant" stuck and among the Senex and Juvex families, the Quadrant is still referred to as part of the Middle Rim, while officially being part of the Outer Rim.