a clan of Mountain giants believe a human mage can lead them to victory against the slightly superior Mist Giants of a neigboring mountain…their ancient cave drawings (think Bayern Tapestry on cave wall) tell them so…
A desolate region is almost entirely without normal vegetation. Local plants are able to unroot themselves and crawl along the ground in search of water and fertile soil. The inhabitants fence their crops in to keep them from wandering off and put heavy stone thresholds in the doorways of their huts to keep wayward plants out.
The plants sense by chemical cues, lacking sight or hearing, and tend to avoid herbivores or anything that smells of "dead plants". Characters with horses are likely to be unwelcome among the locals.