I think you’ll find 25-30km a day is very optimistic once you need to account for people having to make and break camp and forage for supplies along the way too

I think you’ll find 25-30km a day is very optimistic once you need to account for people having to make and break camp and forage for supplies along the way too and you need daylight for that. Those distances might be doable within the developed areas of an empire when you are moving between established settlements or way points with established infrastructure but not when there is no where to rest and no where to eat.