Thousands of years ago, there existed the Great Kingdoms. The races had grown so culturally and intelectually that no one had to work, no one got sick, and everyone was happy. Then the barbarians came. Raging out of their frigig northern homelands, the barbarian's ravaged through the Great Kingdoms to the Great Desert, destroying all. The Grat Magi who made it possible for an entire nation to eat and cloth themselves without effort were slain, their books burned. The Barbarians claimed that the Great Kingdoms had grown decadent and lazy, they deserved to be culled from the tribes of humantiy.
Years of chaos followed. Slowly order returned. The dwarves had retreated to thie mountain homes. The elven warrior/mages watched the borders of the forrest retreats of the elves. Humans, alone, began to rebuild their civilization. Small towns and then cities. Nations have only reformed in the last several centuries, with smaller kingdoms growing and merging.
Remnants of the ancient fortunes still remain, scattered amongst the landscape. Warded with magic and monsters, many of these ancient tombs still house wonderful treasures, mixed with horrible death. Many young heroes find these storehouses of wealth. Some of them even claim the rewards.
The Ancient Elves have retreated to the deep forrests, and none are welcome in their forrest refuge. The stolid dwarves tunnel evermore in their montain homes. Thrifty halflings, trusted by none, play the trade routes of humanity, gypsies and merchants.