In pre-historic times the Western desert is thought to have been a semi-arid grassland, home to savannah animals and hunter-gatherers; evidence of abundant wildlife and surface water can be found in the cave paintings of the Gilf Kebir. It is thought over-grazing and climate change led to desertification and the current geography. Even after this, the oases remained inhabited, and the Antiquities Museum at Kharga has artifacts dating back to the time before the early Egyptian kingdoms.