The Nyrian system was an alleged star system.

According to Dammar, the system consisted of a red giant and at least five planets, Nyria III containing a colony of his species. Beyond the fifth planet, there was a large cloud of interstellar dust.

According to captain Kathryn Janeway, it did not sound like any system visited by USS Voyager, at least as of 2373. It was theorized that the system could potentially be thousands of light years removed from Voyager's position. (VOY: "Displaced")

This system was only mentioned in dialogue.
According to Star Trek: Star Charts (p. 87), the primary of the Nyrian system was named Nyria. The system was visited by USS Voyager on stardate 50912.