The Cybriss Valley is an area on Qo'noS, known for its agriculture and for producing a type of wine. It was once part of the lands of the House of Mogh and Mogh himself had a hunting lodge there, where he and his family once spent a summer in the early 2340s.
In 2372, the Cybriss Valley was taken from the House of Mogh after Worf opposed Chancellor Gowron's invasion of the Cardassian Union. The valley was transferred to the possession of the House of Maang and Ton, the eldest son of the house, claimed the valley was flourishing under their control. (DS9 novel: The Tempest)