Proving Grounds is a place on the planet Longinus. A series of ridges along the western parts of the Outlands marks the limit of Proving Grounds area of Longinus devoted to smaller, shorter fights. The area was originally mostly jungle but intense fighting has led to deforestation and soil begins to wash away, within 50 years Proving Grounds may very well be a desert.
Combat this is usually done by companies from 100 to 300 soldiers to the Battalion 2-6 business levels as individual squads are generally too small to merit the expense of transporting them and complete regiments are so great that it makes more sense to deploy an entire civilization against the current champions of the Outlands. The settlements in the Proving Grounds are simple and casual they are really camp instead city or fortresses and quickly wiped out of the elements when the residents leave. The combatants are usually not given time to bury their dead or restore fallen comrades possessions the bleached skeletons of former fighters is an eerily familiar sight.
Periodically, a Goa'uld can use Proving Grounds to test new military technology. This is mostly limited to surveillance and counter surveillance equipment, but System Lords engaged in weapons research is too protective of it to show it in front of their competitors. An SGC expedition in the area may well turn up the remains of prototype or failed Goa'uld technology is literally no telling what strange secrets of the jungle holds. (RPG: "First Steps: The Stargate Unexplored Worlds Roleplaying Sourcebook")