Grim... wrote:
Not all the stuff, it turns out.
Yes, for clarity, (I've been experimenting with brevity and it's already gone horribly and demonstrably wrong), it reveals the entire map and puts a load of question marks all over it for the stuff you haven't yet found, once you've wiped out the last Mongol camp.
(Prior to completing the game and killing all the Mongols, it puts a question mark on the map when you get close to a point of interest, there are also multiple 'tells' in the environment to help you find them.)
The question marks relate specifically to 'objective' based stuff, for example a Mongol Camp, a Lighthouse, a Fox Den, a Friendly Camp, a Haiku spot, a Pillar of Wisdom, a Hot Spring, a Shrine, a Duel spot, and doubtless other stuff I've forgotten.
The Sashimona Banner in my above example didn't generate a question mark because it's just a collectible, not an objective. However, from looking at the island I was pretty sure there would be something on it, hence me taking the time to get out to it.