Need names and cultural base for the races in my story. Any suggestions?

A great many years ago, a great evil walked this very lands. Nothing grew where these beasts, these demons left their mark. Behind it, it left a trail of blood. The nations that rose up against it was utterly defeated. No one knew where it came from. By the grace of the gods, salvation came in the form of magic that concentrated at the Northern and Southern mountain ranges that anchors our world. Thunderous storms raged in the North giving its people ociated magical powers, whereas in the South, volcanoes erupted and fire sprang from the earth giving them their ociated powers. It was on the Great Central Plains that the Northern Lords of Thunder and Lightning met the Southern Lords of Fire and Flame and defeated the Beast and its dark host and banished it to the Dark Realm. Together they built the Fortress of the Guardians to guard against the return of the Beast, for it vowed its return.