The Orsa system was a star system located at the edge of the Tabula Rasa spatial anomaly. In 2292, it was one of the first systems to emerge from the anomaly, and did so on the borders of Klingon space.
It contained at least one planet, Taal. Taal was wealthy in dilithium, and as a result was the first world targeted by the Klingon Empire in their campaign to annex the region. (TOS video game: New Worlds)