The Umbra Clan (also known as Dark Adepts) is a tribe revealed in Golden Sun: Dark Dawn. Little is known about the tribe, except that some of the Tuaparang, such as Blados and Chalis, are members. Despite the name similarities, there is no apparent connection between the Umbra Clan and the Umbra Gear.
Umbra (the Latin word for "shadow") refers to a shadow's darkest part, where light has been completely blocked out by another object, resulting in total eclipse. The term is usually applied to astronomy to describe shadows cast by celestial bodies.