In 2369, upon escaping from Celtris III, an away team consisting of Jean-Luc Picard, Beverly Crusher, and Worf were to rendezvous with the USS Enterprise-D in this system. Aboard the Enterprise, as Captain Edward Jellico was in negotiation with Gul Lemec, he ordered Commander Riker to pilot a shuttlecraft to the rendezvous point. Riker returned to the Enterprise with Crusher and Worf. (TNG: "Chain of Command, Part II")
Background information Edit
This system was only mentioned in dialogue.
According to the script, the pronunciation for Lyshan was "LYE-shin".
According to Star Trek: Star Charts (p. 46, "United Federation of Planets I") and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), there was a planet named Lyshan in this system, which was located in the Alpha Quadrant. This trinary system consisted of an A-class star, a F-class star, and a G-class star. In 2378, Lyshan was listed as a Federation member.
According to the Star Trek Encyclopedia (4th ed., vol. 1, p. 492), the Lyshan system was a Federation system.