Tepe Sialk

Kashan, Irán

Settlements in Sialk date back from 6000-5500 BC.[2][3]

Tepe Sialk was an important metal production center in central Iran during the Sialk III and Sialk IV periods.
Sialk IV level begins in the second half of the fourth millennium with links with the Mesopotamian civilizations of Uruk and Jemdet Nasr. Later on, the material is similar to that of Susa III (Proto-Elamite level)

Economic tablet with numeric signs. Proto-Elamite script in clay, Susa, Uruk period (3200 BC to 2700 BC). Department of Oriental Antiquities, Louvre.

The ruins of what would be the oldest Ziggurat in the world are found at this same Sialk IV level.