On many worlds without well-established rail or air networks, ground transportation of goods is the only practical option. While city- and road-bound vehicles often favor compactness, those designed for long-haul journeys, often thousands of kilometers, find that maximizing the load carried by a single vehicle is the easiest option. The concept of land trains dates back a thousand years or more, and is most often attributed to Old Terra's Australian continent where vehicles like this crossed its interior desert with cargo from one side to the other of that nation. Over the centuries, land trains have become a haven of the Gypsies and other other similar families that never stay in one place, only stopping long enough to trade or pick up new cargo before going on to their next stop. The arrival of a land train is often grounds for a celebration, especially in towns that have no other contact with civilization. Land trains often give up some of their impressive cargo capacity to mount weapons to protect them from predators, whether they be animals or human.