The main reason why life in the Sahara cluster around oases is because oases offer a supply of water. The Sahara desert is a dry and arid region, with very limited sources of water. Oases, on the other hand, are areas where water is naturally available, typically in the form of underground springs or wells. This makes oases extremely valuable and attractive to people living in the desert. In addition to providing water for drinking, oases also support the growth of vegetation, allowing for agriculture and grazing of livestock. Therefore, oases can sustain human settlements and provide the necessary resources for survival.