The T-Rogorans were a species native to the Gamma Quadrant.
During the 16th century, they conquered a race of farmers known as the Skrreeans. The T-Rogorans killed most of the Skrreean leaders, and forced the rest of the population to work as laborers and servants.
This species was only mentioned in dialogue.
The T-Rogorans were also referred to as "Tirogorans" in the episode's pronunciation guide, which pronounced their name as "Tuh ROG-or-RANS".
According to Star Trek: Star Charts (pp. 70, 74), the T-Rogoran were from the T-Rogoran system. This was a trinary star system with a F-class star, a M-class star, and a G-class star. T-Rogoran was a M-class planet. The official name for the planetary government was T-Rogoran Prime, and this government was annexed by the Dominion in 2370. The dominant species were the T-Rogoran and the humanoid Skrreea. There was no information on the population of the T-Rogoran. The T-Rogoran were warp-capable in 1570.
According to the Star Trek Adventures - Gamma Quadrant sourcebook, the T-Rogorans resembled Earth crustaceans, however, they were not adapted to aquatic environments.