Chancellor Gaumen was a representative of the B'omar Sovereignty. He led the negotiations with the crew of the USS Voyager to discuss passage through B'omar space. The B'omar were very xenophobic, and Dumah laid down many restrictions on Voyager – they could not exceed warp 3, they had to avoid the planets and colonies of the B'omar, and they had to stop for numerous inspections.
After Seven of Nine entered their space looking for the ship she and her parents were on before their assimilation by the Borg, Dumah reacted violently and ordered his ships to fire on Seven. Voyager had to go around their territory. (VOY: "The Raven")