Urbanization first developed in the Fertile Crescent region due to favorable conditions for agriculture and the need for defense. The earliest known urban centers were Jericho around 8000 BC and Catal Huyuk in Turkey around 6250 BC. Urbanization was delayed in China until the Shang Bronze Age potentially because the native crops and animals provided a less nutritious diet compared to the Fertile Crescent, and competition for land was initially less in China so defense was less important.