Professional nomads Land may at any time be altered by natural or man-made means, so there has never been any such thing as a "permanent map," and all survey maps have to be updated.
土地受天然或人為影響，隨時會有變遷，地圖自然也需隨時調整更新，本來就沒有一勞永逸的「萬年地圖」。