Nequencia was a binary star system in Romulan Star Empire space in the Beta Quadrant, consisting of a G class primary star and a M class companion star. (ST reference: Star Charts) The system had at least one planet. (ST TNG CCG: "Sensitive Search")

The Nequencia system could be visually seen from Space Station KR-3. In 2311, Elias Vaughn stood in front of a viewport on the space station and tested his memory, naming all the major stars he could see in Romulan space. (TLE novel: Serpents Among the Ruins)

Ngoj was killed in this system by the Romulans. (ST novel: Excelsior: Forged in Fire)

In 2381, the planet was attacked by the Borg. (ST - Destiny novel: Lost Souls)

At one point, the Federation, Romulan Star Empire and Klingon Empire investigated reports of an information dealer's "politically 'sensitive'" activities in the sector. (ST TNG CCG: "Sensitive Search")