The document discusses the uneven global distribution of population, identifying four major population concentrations in East Asia, South Asia, Southeast Asia, and Europe. It also notes two emerging population clusters in Northeast USA/Southeast Canada and Western Africa. It defines ecumene as densely populated areas and non-ecumene as sparsely populated. It lists four sparsely populated regions - dry lands, wet lands, cold lands, and high lands - and asks to explain the reasons each is inhospitable for human habitation.