How does geography change humans?

Geography has historically affected where people can settle, and why they settle there.

Early humans were bound by larger geographical boundaries, that often limited or directed expansion of the human race across the globe.

Prior to large boats certain portions of the world were not habitable or reachable, deserts posed similar problems as they could not sustain any large settlements.

People normally settled along the banks of rivers as these provided water to drink and irrigate with, fruit and vegetables as well as a method of transport. The larger the population the more resources were needed and the more complicated the settlement would become in order to sustain itself (dams, grain storage, Plumbing etc.).

Other geographical concerns are altitude, humans struggle to live in low oxygen environments, therefore many high lying areas are simply uninhabitable, normally with altitude comes cold as well, compounding the problem.

Geography and climate are normally interlinked, equatorial areas have high rainfall, abundant plant growth (which is sometimes also a barrier), but also harbor some of the most horrible diseases and venomous creatures on earth.

Polar regions are harsh, lack of food, and the extreme environment allow only the most adapted and hardy of humans to survive.