The Promellians were a technologically-advanced humanoid race that were the cause of their own extinction during their long war with the Menthars, that ended with the battle at Orelious IX sometime during the 14th century.

The Promellians operated advanced battle cruisers which operated at a technology level that rated as rather crude in terms of 24th century Federation technology, but were highly advanced for their time. They also used a form of information storage device that was a crude analog of a 24th century Federation isolinear optical chips. (TNG: "Booby Trap")