I am preparing a sandbox adventure cycle, which I will possibly eventually package into a module. I will post much of the background to it here (possibly omitting those details that would not be player knowledge).
Without further ado:
The fall of the Empire drove smallfolk around the northern fringes of the settled lands deeper into the hills and mountains of the Worldspine to avoid the centaur khans and the humanoid bandits that prowled the wastelands. Beyond the Hungry Ghosts the settlements were especially exposed and the southern fringes of the Great Steppe were almost completely depopulated. Further east the survivors pushed, some prospered, most perished.
One group under Goodlord Verdek settled a high, wide valley that nestled among the peaks of the Tibur, with narrow defensible approaches to the northeast and steap pass leading west. There they fought off the centaurs of Khan Enkurtz and eventually established a little barony in the valley and called it Sant Nomme. Iron and mercury ores were found, farming communities were established, trade began to come to the barony and things seemed to be settling down, despite the fall of the old order.
Then the long winter came.