[brandall10]

That's near term thinking. Longer term thinking had the # of people who were living sustainably OTG to be a vastly small minority of the populace, hence everyone aside from immediate family members were your enemies.

In regards to population density, the further groups had to travel on limited resources the more dispersed and weaker they would be, and in turn the amount of resources available would be more dispersed relative to lack to nearby neighbors, all of which would be reasonably well protected.

Basically, you want to be relatively well fortified slim-pickings that are hard to reach.