The most magnificent ancient site of Bisotun area (Kermanshah Province, west of Iran) is Darius I’s Bas Relief and Inscription, carved around the year 520 BC. The site recites the Darius the Great’s victory over Geomata the Clergy and nine other rebels. Twenty meters long and eight meters high, the property includes an inscription of 1119 lines in Old Persian, Elamite, and Akkadian (Babylonian). In addition to its historical value, the inscription of Bisotun is one of the oldest encyclopedia of proper names in Iranian languages to the extent that it functions as a valuable treasure to investigate historical changes in the words of the languages of the various periods; such words include proper human names, as well as the names referring to cities, rivers, and mountains. It also plays the role of an ancient source of information on writing, calendar, ideologies, and the thinking traditions of the period.