"It was probably a way to affirm the ownership of the territory by a small prince or king at the time,"
Frustratingly I can't find a lovely quote I stumbled across recently that was (poorly paraphrased) something like 'Small men pointing at things on a map is the leading cause of war'.
It might have been from one of Simon Winder's superb European trilogy.
Certainly there does seem to be a trend amongst insecure monarchs and dictators eager to accurately audit their domain, and identify the neighbouring realms that desperately need to be liberated from their current owners / occupants.