Tal'lhnor Gates was a black hole that was near the Romulan border and was the Klingon Empire's primary energy production facility until 2291. During the Klingon Civil War of 2291, Melkor, son of G'Iogh offered the Romulan Star Empire possession of several important systems, including the Tal'lhnor Gates, in exchange for support to attain leadership of the Imperial throne.

The black hole was unfortunately destroyed when Melkor ordered Brigadier K'mak to detonate a powerful gravitational attenuation device as an act of spite, rather then let it fall into General Chang's hands. (TOS video game: Klingon Academy)