Jericho has evidence of settlement dating back to 10,000 BCE. During the Younger Dryas period of cold and drought, permanent habitation of any one location was impossible. However, the Ein es-Sultan spring at what would become Jericho was a popular camping ground for Natufian hunter-gatherer groups, who left a scattering of crescent-shaped microlith tools behind them. Around 9600 BCE, the droughts and cold of the Younger Dryas stadial had come to an end, making it possible for Natufian groups to extend the duration of their stay, eventually leading to year-round habitation and permanent settlement.