The Moroans were physically distinguishable by their big ear lobes, yellow-green skin, four fingered hands, arms with needle or feather-like protuberances on them, tusk like teeth jutting out of the jaw bone, and yellow eyes with no pupils. (TOS comic: "Tests of Courage")
The Maroan Dominion, under the leadership of Supreme Leader Brekara, received support from the Romulan Star Empire and Admiral Jaricus. The Maroans promised the Romulans that their intelligence network would be able to help them in conquering worlds without the Federation and Starfleet knowing about it. They were able to equip their ships with antiquated Romulan cloaking devices.
In 2290, after Tabuk 3 and 4 were admitted to the federation, the Maroans launched a raid on a Tabukan cargo ship carrying weapons and taking them. When Starfleet dispatched the USS Enterprise-A and the USS Excelsior to the Tabuk system, the Maroans and Romulans hatched a plan that involved in separating the two ships. They then launched a gas attack on Epsilon Kitaj forcing the Enterprise to respond and leave the Excelsior alone in the Tabuk system. After the Enterprise and the Excelsior separated, the Maroans attacked the Excelsior briefly. Adm. Jaricus and Supreme Leader Brekara then sent Commander Horalt to attack the Tabukan convoy the Excelsior was escorting. They were informed by Brekara's son, Commander Vodrin that the Enterprise was leaving Epsilon Kitaj. Brekara ordered Vodrin to return to the Tabuk system, but he refused to do so.
Vodrin and his forces then move to occupy Epsilon Kitaj, blockading it. However, Vodrin allowed the physicians aboard the SS Salutaris to go the surface if they offered no resistance. During the occupation, the Maroans executed crews and destroyed ships that tried to run the blockade. However, the colony's resistance movement bombed Vodrin's headquarters. The terrorists were caught and executed. However, Vodrin received medical care from Drs. Wilson and McCoy despite his protests. Commander Bortser, then ordered them to withdraw and leave Vodrin on Epsilon Kitaj when the Enterprise returned. However they were destroyed by the Enterprise.
In the Tabukan asteroid belt, Commander Horalt's forces attacked the weapons arsenal when an insider disabled the back-up shields. However the Excelsior arrived force him to withdraw. Sometime after the arsenal caught on fire and explosions started. The Maroan taskforce, under the personal command of Brekara, moved in to attack the arsenal. She then sent in a assault team in to take the warheads. However the team was captured by Commander Rand and a security team from the Excelsior. The taskforce was the approached by both the Excelsior and the Enterprise. Horalt to ensure Brekara's escape ordered his ship to collide with Excelsior. The Excelsior was able to change course and avoid the collision with the Maroan ship which was destroyed. The weapons were then destroyed, thus ending the alliance between the Romulan Empire and the Maroan Dominion. (TOS comic: "Tests of Courage")