Once upon a time...
Behkesh captured Jotheb and held him for ransom, which was paid by Jotheb's Consortium of Trao. Anyway, during Jotheb's last days in Behkesh's custody, Behkesh kidnapped a Hynerian Dominar named Rygel XVI. Jotheb and Rygel had adjacent cells in Behkesh's prison camp. Rygel, the egotistical guy that he is, bragged endlessly about Hyneria and his life as a Dominar and all that yotz. Jotheb then one-upped him at every turn. Later on, Rygel was murdered by Behkesh during an escape attempt. Jotheb, seizing this opportunity to get billions of Hynerian subjects into the Consortium of Trao, brought Rygel back to life.
However, when Jotheb dropped the first shoe on Rygel, Rygel dropped the second shoe on Jotheb (for once) by saying that he was a deposed Dominar, and had no subjects at all. "Ransom me if you want, but all you get is me!" This made Jotheb incredibly angry, so he hatched a plan. Soon after that, Behkesh released him. Jotheb high-tailed it back to the Consortium of Trao, and organized his military. Then, he took is armies to the Hynerian Empire, and sacked it. Massive genocide.
To sum up, now Rygel is the only Hynerian left. That's why we haven't seen any other Hynerians.