First of all they usually settle within walking distance to a source of fresh water - some areas in Israel are the great exemption here. And there is plenty of

First of all they usually settle within walking distance to a source of fresh water - some areas in Israel are the great exemption here. And there is plenty of reason: * historic: a lot of trade routes for sought-after goods went through deserts * economic: rich fishing grounds just off the coast - see Western Sahara for an example (Boujdour and Dakhla being the main cities) * economic: a lot of nomadic farmers live in deserts because they provide just enough food for the livestock * politics: keep disputed areas occupied (Israel and Western Sahara as examples) * politics: borders - these things tend keep people from freely moving to more hospitable areas * nature: some think deserts are beautiful (count me in) * spiritual: very low population density and a very tight connection to the forces of nature appeal to some people