People of various cultures have lived in the peninsula over a span of more than 5,000 years. The Dilmun culture, along the Persian Gulf coast, was contemporaneous with the Sumerians and ancient Egyptians, and most of the empires of the ancient world traded with the states of the peninsula. Except for a few major cities and oases, the harsh climate historically prevented much settlement of the Arabian Peninsula. The earliest known events in Arabian history are migrations from the peninsula into neighbouring areas