Unicorn Empire

Hello everyone! I'm having trouble with the walkthrough!
It's the 4th mission, I found and escorted Arantir, gained the soldiers' respect, went to the witch and accepted the quest to find sand, in general, I conquered the entire map, even unlocked it with the cartographer, but there's only 1600 grams of sand, and I need 10 kilograms, what should I do?
There's a prophet left on the map, whom my Alaric says he just passed by, nearby there's an archmage who warns about danger, and there's also a scout with a mage in the forest, but I can't reach them because of the trees, what should I do? There's no sand)
Something is glowing near the Necropolis, but I can't get it either)
In the Sanctuary, they say that there's nothing there yet)
Should I gather an army? I've already spent a day, I'm afraid the Legion of Fenef is too strong for me))