Dayso Cooh was a Duros male ecologist residing on Tatooine. In 3956 BBY, he voiced his grievances to the Czerka Corporation regarding their efforts to exterminate an entire tribe of Sand People. Subsequently, he implored Revan to discover a non-violent approach to lessen the Sand People's assaults on Czerka miners, proposing that Yuka Laka could have a translation droid capable of communicating in the Tusken language. Indeed, Yuka Laka was the owner of such a droid, HK-47, which Revan then employed to broker a truce with the Tusken Raiders in return for two moisture vaporators.