Mari Letters. The Mari Letters (early 18th century bc) include several references to census taking. The Akkadian verb used in these instances is ubbubum and the noun is tēbibtum, both of which usually relate to purification; however, at Mari the terms relate to registering soldiers during a religious ceremony (Dalley, Mari and Karana 141–145; Speiser, “Census and Ritual Expiation,” 17–25).