Overlook
White man came, across the sea…(whoops, wrong band).
Anyway, the Chieftain overlooks the valley and can see progress on the horizon, so he thinks "If you can’t beat them…".
So the invaders (wrong band again!) may well have some items to trade, eventually (or perhaps sooner [big hint to completing the map]).
About 40 minutes for this one, but it’s been done in less!