Carraya IV was a planet near Romulan space, located in the Carraya system in the Azure sector of the Tau Dewa sector block in the Beta Quadrant. (TNG episode: "Birthright"; STO mission: "Carraya System Patrol")
In the 24th century, Klingon survivors of the Romulan attack on Khitomer were taken to a prison camp on Carraya IV. The planet featured several jungles and lacked fortifications. A few Romulan soldiers guarded the prisoners and supply vessels made regular stops at the planet.
In 2369, Jaglom Shrek, a Yridian information dealer, approached Worf during a visit of the USS Enterprise-D to Deep Space 9. Shrek believed that Mogh, Worf's father, was being held at the camp so Worf investigated the camp. Worf was able to find the colony and was held prisoner for a time but was eventually allowed to take several young Klingons back to the Federation with him. (TNG episode: "Birthright")
The Klingon Empire had made plans to colonize Carraya IV, but in 2404 the House of Martok used political pressure to block the proposal. It has since dropped off of Klingon expansion plans. (STO mission: "Carraya System Patrol")