Sacro was a planet located in the galaxy's Alpha or Beta Quadrants. It was the homeworld of the Karman civilization.
History and specifics[]
In 2266, on Sacro several Karmen seized a USS Enterprise shuttlecraft and imprisoned James T. Kirk, Spock, and a commander in the sciences division. The officers escaped through a dangerous tunnel containing a variety of obstacles, broke through an airlock, and beamed safely back to the Enterprise. (TOS - Star Trek Annual 1977 comic: "The Tunnel of Death")