The Iranian Plateau is, in the late 4th millennium B.C., with Mesopotamia and Egypt the birthplace of writing in the World. We propose here to consider the Proto-Elamite (Early Proto-Iranian) and Linear Elamite (Late Proto-Iranian) scripts, not as two different writing systems, but as the same system at two different chronological stages of evolution. Between 3500 and 1850 B.C., the continuous history of writing in Iran may be consequently understood according to 6 distinct phases (I: 3500-3300 B.C.; II: 3300-3000/2900 B.C.; III: 3000/2900-2300 B.C.; IV: 2300-2000 B.C.; V: 2000-1850 B.C.; VI: after 1850 B.C.).
