This seal, of pale green volcanic tuff, is derived from earlier Uruk-style seals depicting animals, but belongs to a stylistic tradition found not in Mesopotamia but in south-western Iran. The heavy emphasis on the shoulders and haunches of the animals divides the bodies into three segments which are often patterned. Some seals of this type were impressed on tablets bearing the Proto-Elamite script which died out later in the third millennium. On many of these Proto-Elamite seals animals adopt human postures and these may have led to the appearance in Mesopotamia of such creatures as the bull-man and human-headed bulls. At the end of the fourth millennium BC, the widespread Uruk culture of Mesopotamia disappeared. The site of Susa slipped out of the Mesopotamian cultural sphere. Instead it shared a ceramic tradition and a writing system with the site of Anshan (modern Tal-i Malyan), which lay about 500 kilometres (as the crow flies, and about 800 by road) to the south-east and later became the Elamite capital. Proto-Elamite remains have been found across a wide area of the Iranian plateau. However, between 2700-2500 BC the Proto-Elamite sites disappear, while the Mesopotamian cities begin to reassert their presence in the east through military action.