Small, but very useful in the right hands.
While long distance travel has long been performed, the speed had long been on the low end. This was due to the fact that the normal beast of burden, the Lurkogia, are rather slow and walking is not much faster.
The sand barges were initially made as a way to prove that one could get across the known world in less than 15 days. This was achieved, but the vehicle was disassembled upon arriving back at the starting point, so it was forgotten how to construct such a thing.
That didn't stop people from trying and very recently a prototype was successfully demonstrated to work, even if it doesn't look like the original description.
The government has taken a great interest in it as a military vehicle and as a way to speed up communication across the lands. A few more will be built and tested in harsher environments before being widely deployed.
Due to the fact that it is a new creation there are many design changes happening all of the time, many of which are not well documented. Everything from the size and shape of the sail to the shape of the hull is different for each new barge built.
There are two sails which use the relatively constant wind in the desert and grassland in order to propel itself forward at a high speed, especially compared to what can be conventionally be achieved in the desert.
In order to reduce the friction on the sand wide wheels are used. In case the ground gets to soft the Barge cannot move without someone or something dragging it along.