A cylinder seal is a small round cylinder, typically about one inch (2 to 3 cm) in length, engraved with written characters or figurative scenes or both, used in ancient times to roll an impression onto a two-dimensional surface, generally wet clay. According to some sources, cylinder seals were invented around 3500 BC in the Near East, at the contemporary sites of Uruk in southern Mesopotamia and slightly later at Susa in south-western Iran during the Proto-Elamite period, and they follow the development of stamp seals in the Halaf culture or slightly earlier.