The Idanians were an intelligent humanoid species. They were a secretive race, and so did not have much contact with other civilizations, though they had a government which included an intelligence organization.
They had distinctive cranial ridges. Typical clothing for both male and female Idanians included a cowl over their heads.
During the 2370s, the Idanian authorities took a particular interest in a member of the Orion Syndicate named Draim, who operated from the planet Finnea Prime. In 2371 they sent an intelligence operative named Arissa into his organization, who, for two years collected information on Draim so as to potentially cripple his entire organization. (DS9: "A Simple Investigation")