Modern Iran is roughly equivalent to Persia and including in its southwestern part ancient Elam. The ruins of many famous ancient cities, like Eridu , Ur, Nippur and Kish are now far from the river, but were in the past situated at the river banks. After 8000 BCE Near Eastern environments become substantially more attractive for human settlements. The Atlanticum is the period in which agriculture developed in the Near East, around the Nile in Egypt and in the Indus valley in India. Sumerian has no known relation to any other language.
Cylinder seals are a typical Sumerian invention.
Such seals were also used in the Sarasvati-Sindhu civilization. The cylinder was roled over wet clay to mark or identify clay tablets, envelopes, ceramics and bricks. It so covers an area as large as desired, an advantage over earlier stamp seals. Its use and spread coincides with the use of clay tablets, starting at the end of the 4th millennium up to the end of the first millennium. After this time stamp seals are used again.