In the Physics section, everything should be explained in detail. It is affected by the hero's specialization (if it's Logistics, and sometimes if it's a monster specialist), the Logistics skill, Stables, Gloves (one pair), and Boots. For example, a monster specialist like Turis can travel further if he only camps in stables. The ability to traverse swamps depends on whether the entire army is composed of swamp creatures or if there is a Pathfinding expert. You can walk on sand without penalty if there is at least one Nomad in the army.