Dumah is one of the two B'omar representatives in The Raven who grudgingly offer Voyager a tortuous, heavily restricted route through their space and react with fury when Seven of Nine crosses their border.
Dumah is a representative of the B'omar Sovereignty, a suspicious and territorial Delta Quadrant power, seen in the fourth-season Voyager episode The Raven.
Together with his colleague Gauman he comes aboard Voyager to discuss Captain Janeway's request to cross B'omar space. The pair treat the talks as a favour, laying out a winding course that avoids every inhabited or industrial system and attaching a long list of conditions on speed, scans and weapons.
When Seven of Nine, drawn by a Borg homing signal, takes a shuttle straight into B'omar territory, the two officials break off negotiations and demand that she be hunted down, leaving Janeway to recover her crew member without their consent.