They are humanoid in appearance and live in the Alpha Quadrant. Their home planet is named Acamar III.
Leaving behind a traditional history of clan rivalries and violent feuding, they had enjoyed peace for nearly a century in 2366. The exception to the reconciliation were the Gatherers, a segment of the population that split from the more conservative Acamarians and refused to be a part of the peace settlement and since then lived offworld, as nomadic interstellar marauders, believed to have been responsible for numerous raids on various outposts and ships in the sector near Acamar III.
Physically, they can be identified by a formed indentation in their foreheads, and bear traditional tattooing of the face. Their blood is composed of an odd composite of iron and copper based blood chemistry. This is rare in most other species in this area of the galaxy.
Their culture places much importance to clan membership, both socially and in political circles. In earlier eras, clan warfare was notoriously violent. One such feud, between the Lornak and the Tralestas, lasted almost three centuries, and ended only after the last Tralesta was killed.
Their government was headed by Sovereign Marouk in 2366. In that year, she offered a repatriation for the estranged Gatherers. Jean-Luc Picard of the Enterprise-D at that time help with negotiations to reunite the Acamarians and the Gatherers. This took place at a gatherers camp on planet Gamma Hromi II. Negotiations finally paid off and eventually the gatherers agreed to return home the same year.
First seen TNG: The Vengeance Factor