Along the northwestern border of Eternalfold (a world from my dreams) there is a vast mountain range that's devoid of most life and infested with supernatural demonic creatures and dragons. Scattered throughout there are carved stone gateways that the demons believe will bless them before they raid their neighbours (they're an extremely superstitious and ritualistic bunch). This painting gives you an idea of what a small gate and its keeper would look like. The top of the carved stone there is a little over 20 feet in height, while some gates can have carvings that are thousands of feet in height, hundreds of feet apart and are protected by a suitably larger and more twisted creature. Somehow long ago it was discovered that recarving the stones to mirror images of each other would create a seal that no demon would want to venture through and now the kingdoms closest to the mountains spend large amounts of resources forming expeditions to find and seal the most threatening gates. This has led to the creation of many specialized fighting guilds, martial arts styles, and scholars who focus on warfare with demons and the supernatural. Although demon gates cannot be created the vast scale of the mountain range (it would take a lifetime of travel to explore just the border of it) has left generations of warriors and kings with plenty of problems. The mountains have a way of making even huge and immobile objects remain hidden for eons. It often appears that for each gate recarved another three are discovered.