Crossroads!
1630 CE, in the misty past of Britain’s history, there was a prince named Mordred, and his bastard half brother, Arthur.
Essentially, Arthur and his knights convert to Christianity after a decade of regency in his younger brother’s name, and longer as the protector of Britain, by right of arms and by his aquisition of the protector’s sword Caledfwlch.
At this point, Mordred refuses conversion, and Arthur ousts his brother.
War ensues, and where things really take a turn is when Mordred makes a deal with The Morrigan to provide her an empire ruled by her half-mortal children and dedicated to the gods in exchange for the power to defeat his brother.
More than a thousand years later, the Empire of Cymru rules over what we call the British Isles, France, and most of Western and Central Europe, the Mediterranean, and has strong alliances and growing trade towns in the New World. Magic has never left the world, and the heirs of Mordred are shadowy people with long lives and a daring and sometimes wild nature. The Empire is strongly Pagan at its core, but functions in a sort of federalism inspired by the ancient Persian empires, meaning that parts of the empire are nearly fully autonomous, and have thier own petty monarchs or parliaments or whatever.
It has several rivals,
Federation of Reykjavik (and “empire” made up of Scandinavian states, the free states of Greenland, and the nations of the Iroquois Federation
The Byzantine Roman Empire persists, and is the primary bastion of Christianity in Europe.
The Caliphate rules over much of the historical territory of the Abbasid Caliphate, excepting Egypt, Persia, and some other little bits. The rise of the “moralists” was avoided, so this is still an empire that values science and the exchange of ideas.
Catholic Spain is small, made up of only a few northern kingdoms not part of Al Andulus or the Empire of Cymru’s Iberian holdings, and a widespread but tenuous diaspora spreading from the West African coastline to the islands and coasts of South and Central America, in walled fortress cities that are as likely to be embattled with their neighbors as have open trade relationships, from decade to decade.
The PCs in the 1630 attend thier first year at the Royal Academy in Cardiff, where many of the most promising youths of the Empire and her allies and rivals go to learn, to meet the powerful scions of far flung houses, and to compete in a sport that combines parkour with rugby.