The history of the human species is a history of migration. From small centres in Eastern Africa, humans have migrated to all known places on the planet. Massive migrations have affected all known land masses and all indigenous peoples, who were themselves prior migrants to sometimes empty lands. Deforestation and expanding agriculture in the Americas, expanding agriculture and plantations in Central America and Southeast Asia, and expanding oil production in the Middle East are only some of the more recent and dramatic examples of the environmental impact of migration. National planning for international migration and sustainable development confronts two conflicting interests, streams and problems: those dealing with out-migration and with in-migration. A country may be subject to small immigration flows that can destabilize fragile environments, and lead to ethnic conflicts with indigenous peoples. A useful planning tool for internal migration is to map what can be called population–environment hot spots.