Carraya IV
Carraya IV is a planet near Romulan space, located in the Carraya system. It is also home to the arboreal needle snake.
Klingon survivors from the Khitomer Massacre were brought to a prison camp here following the battle, and eventually learned to live in peace with their Romulan captors. The planet contains several lush jungle areas, and was not heavily fortified apart from a few Romulan soldiers. Supply ships made regular stops at the world.
The colony was kept secret until 2369, when a Yridian information dealer named Jaglom Shrek approached Lt. Worf with knowledge of the camp during an USS Enterprise-D visit to station Deep Space 9. Shrek believed Worf's father, Mogh, was alive on Carraya IV, leading Worf to investigate. He found the colony and was initially held captive there, but was allowed to return to the Federation with several Klingon youths who wished to leave their secluded home. They were brought to the Enterprise aboard a Romulan Warbird, and sworn to secrecy about the prison camp in order to protect the honor of the Klingons who remained behind. (TNG: "Birthright, Part I", "Birthright, Part II")