Each of the altars is constructed of solid limestone. All three contain a dedication inscription, which is carved around all four sides of the altars in the South Arabian script of that period, and each bears the name of their donor: Bi'athar . The first altar was dated to between the seventh and sixth centuries B.C by French researcher Christian Robin . Since Naw'um of the tribe of Nihm was the grandfather of Bi'athar, it is estimated that the Nihm tribal name must be at least two generations older than the altars themselves .