“The allegation is that the population was scanty.”
Who? When? Where were such “allegations” ever made?
I guess you’ve never read the histories of battles there where the colonists only succeeded with their superior armament, against what seemed overwhelming numerical odds.
Battles which occurred at exactly what stage of what events?
The story we’re seeing above was that opposition from natives who lived north of the Boer-settled area trying to occupy the area afterwards. These natives didn’t care about South Africa till they saw what the Boers could do. Then jealousy overtook the natives.