In a world known as "Earth," in the year 0, magic returned to the land through an event known as the Awakening. Some humans remained, but others turned into elves, orcs, dwarves, and worse. Gods returned in force as dragons and giants rose from the mountainsides. In the swamps, lizardfolk were born, and in the germanic and french lowlands, mice achieved sentience, turning into the mousefolk.
Now, the year is 1400, and the world is in a time of rapid change. Population levels have finally begun to recover from the plague of Justinian in 520AA and the Black Death of the 1340s. The Golden Bull, a proclamation by the elected emperor of the Holy Roman Empire has just been formalized, solidifying the Germanic rebellion from the Roman Empire proper, formally establishing a new, elective monarchy, and causing a near unmendable rift in the Hellenistic religion. In Graecia and Anatolia, alchemists are experimenting with an explosive black powder from the far east that could put the power of a battlemage into the hands of an ordinary soldier. The first factories have begun to be set up in Venecia, each spitting out dozens of ships and thousands of swords for the Roman war machine. In Portugal, new ships are disappearing off of the face of the earth as they travel deep into the Atlantic and, some say, to oblivion. In France, King Theudebert II de Merovingian has just formalized elves as first class citizens and all others as second-class, formalizing an apartheid that had been growing over the last thousand years. In the Nile river valley, Aegyptus has splintered off from the Roman Empire through the resurrection of the last Pharaoh of Kemet.
On Earth, countries, nobles, and armies never stay put. People in power always want something more and they're willing to throw lives to get it. The world has never been more unstable. A single spark could start the fire that topples an empire.