Physically, Karemma were tall and slender with black or dark brown hair that was combed back. They had a head ridge, like Klingons, but smoother and without edges. The head ridge went down and over the nose. The ridge could be slightly seen to the chin of a Karemma. As a result of this ridge, their noses looked very large, and were quite large in the lower end. It was very broad and one line in the skin on each side of their noses pointed downwards to the outer sides of their face. Karemma had normal eyes that were gray, black, or brown. Overall, this gave them a somewhat rodent-like appearance.
Little is known of the culture of the Karemma, but they were apparently a mercantile, trade-oriented race. They loosely seem to have been the Gamma Quadrant analogue of the Ferengi, though in service to the Dominion. Just as the Vorta functioned within the Dominion hierarchy as administrators and bureaucrats, and the Jem'Hadar functioned as shock troops, the Karemma seem to have handled basic trade affairs within Dominion space. Unlike Ferengi, however, Karemma believed in fair dealing and cautious business practices, and regarded cheating or gambling to be taboo.
The first relations between the Karemma and the Alpha Quadrant were established in 2370, by the Ferengi. As the Dosi were not able to meet Grand Nagus Zek's request for 100,000 vats of tulaberry wine, they referred his chief negotiator to the Karemma, allegedly being an important member of something called the "Dominion". (DS9: "Rules of Acquisition")
In 2371, Federation representatives aboard the USS Defiant came together with First Minister Ornithar of the Karemma in an attempt to contact the Founders of the Dominion. The meeting was arranged by Quark, who had previously negotiated the tulaberry wine trade. Ornithar admitted that the only contact the Karemma had with the Founders was through their representatives, the Vorta. He did direct the Defiant crew to Callinon VII, where they had been instructed to send all inquiries. (DS9: "The Search, Part I")
In the following year, the Karemma began conducting trade with the Federation, exporting goods such as Karemman fleece. The Ferengi acted as neutral intermediaries, although they unfairly gouged the Karemma with fabricated taxes and tariffs. A Karemma starship commanded by Hanok met with the Defiant to discuss their complaints about the trade duties. During the meeting, the ships were intercepted by two Jem'Hadar attack ships. All four ships entered the atmosphere of a gas giant, where the Defiant was able to destroy the Jem'Hadar ships and rescue the crew of the Karemma ship. The Karemma manufactured and provided at least one type of torpedo carried on board the Jem'Hadar attack vessels. (DS9: "Starship Down")