Romulan Neutral Zone
From Star Trek: Theurgy Wiki
The Romulan Neutral Zone was an area of neutral space between the United Federation of Planets and the Romulan Star Empire. The Neutral Zone was established after the end of the Earth-Romulan War in 2160. Entry by either side into the Zone constituted an act of war. The Romulans incorporated a map of the Neutral Zone into the Romulan Senate chamber's floor. Source: Memory Alpha
