hi, orious13 suggested i post this here, so i am.
why not have the code for tribal area expansion based on membership size check to see if the new tribe size area collides with any other tribal areas and if it would not collide then expand the area, if it does collide then print an error message.
here's some pseudo-code to help out
new_area_size = get_tribal_area_size(tribe_population)
if check_tribal_area_collision(new_area_size) equals False then
print_error_message("tribal area cannot be expanded due to nearby existing tribal areas")