Map of the Oralian sector in 2380
The So'jan Neutral Zone was a buffer created following the fall of the So'ja Republic, between the United Federation of Planets and the So'ja Coalition. Any entry into the Zone would be considered an act of war. In 2381, the So'ja broke the Zone, crossing it with an armada and destroyed the USS Apollo, thus igniting the Coalition War. (Star Trek: Pioneer: "Fall of the Apollo")