Dralnok

Dralnok was a planet within the Cardassian Union, later taken by the Klingon Empire. A previously unknown chemical substance, designated by the Klingons as Element 604, was discovered on Dralnok. Dralnok was apparently returned to Cardassian control by the end of the Dominion War. 


 * It is unclear whether the war in which the Klingons took Dralnok was the Klingon invasion of Cardassia in 2372, or the later Dominion War.