In the 1970s, to the first crazy skateboarders who were putting big, fat wheels on their banana boards, it was called dirt-boarding, earth surfing, or any other number of names. By nailing loops of old bike inner-tubes on the top of the skateboard, riders were able to strap in and bomb down the closest hill around. This was all-terrain skateboarding at it crudest.
This backyard hobby had a few things working against it: first of all, there were no brakes. Stopping consisted of jumping off at high speeds or trying to power slide the board sideways. This didn't always work so well. Secondly, the boards didn't turn very well. The skateboard truck system tries to slide all four wheels by friction in order to make the board turn. This works alright if you are on a smooth surface and all four wheels have contact to the ground but, that's rarely the case off-road. You basically had to pick a straight line through something (bushes, trees, dogs, etc...) and try to hold it. The short wheel base (length) of the skateboards also made them very unstable, bouncy platforms when going over rough areas and relatively small, hard wheels didn't work on any thing much but hard dirt and short grass.
(some brands even have real steering mechanics), they are burly enough to go in and over stumps, rocks, roots, mud, sand, dirt, grass etc.
Over the years, people kept tinkering with these things and started to make improvements. Longer skateboard decks (3 to 5 feet),and even snowboards were used. Lawn mowers were a favorite thing to cannibalize for their big, inflatable, treaded wheels. Sky hooks for your feet were used in place of the nailed down bike inner-tubes and skateboard trucks were jury-rigged to allow for a wider width and the bigger wheels. Inventors started making frames, to which the decks and wheels were mounted, from stolen shopping carts and old bike tubing. All of these things were leading up to the last few years when the backyard inventors started to really get things together.
Mountainboards, as they are called today, are a hybrid between a snowboard and a mountain bike rather than a burly skateboard. They have greatly improved turning ability, (some brands even have real steering mechanics), they are burly enough to go in and over stumps, rocks, roots, mud, sand, dirt, grass etc. The wheels are like small knobby bike tires, sailboard-style foot-straps are used to catch air with, and some brands have braking systems. In this cross-sport age, riders now include snowboarders, surfers, mountain bikers, aggressive inline skaters and skateboarders