The occupation of grouped hamlets in the area of Susa, as determined by radiocarbon dating, ranges from 4395–3955 to 3680-3490 BC. There are dozens of prehistoric sites across the Iranian Plateau, pointing to the existence of ancient cultures and urban settlements in the fourth millennium BC. During the Bronze Age, the territory of present-day Iran was home to several civilizations, including Elam, Jiroft, and Zayanderud. Elam, the most prominent of these civilizations, developed in the southwest alongside those in Mesopotamia, and continued its existence until the emergence of the Iranian empires. The advent of writing in Elam was paralleled to Sumer, and the Elamite cuneiform was developed since the third millennium BC.