Desert exploration is the deliberate and scientific exploration of deserts, the arid regions of the earth. It is only incidentally concerned with the culture and livelihood of native desert dwellers. People have struggled to live in deserts and the surrounding semi-arid lands for millennia. Nomads have moved their flocks and herds to wherever grazing is available, and oases have provided opportunities for a more settled way of life. Many, such as the Bushmen in the Kalahari, the Aborigines in Australia and various Indigenous peoples of the Americas, were originally hunter-gatherers. Many trade routes have been forged across deserts, especially across the Sahara Desert, and traditionally were used by caravans of camels carrying salt, gold, ivory and other goods. Large numbers of slaves were