Vinland and Firanja is a timeline really similar to ours... until the day the Templars were wiped out.
around 1000 AD the Viking colony of Markland succeeded. This, combined with a series of islands in the Atlantic ocean, was key to the survival of Christianity.
In 1314, after the decimation of the order of the temple, a few Castilian knights who survived found the legendary St Brendan Archipelago and settled there. Between 1347 and 1398 all of the Christian kingdoms but the eastern part to the Novgorod Republic were wiped out by the pest, and the Muslims settled there by 1415, renaming the continent as Firanja.
more details can be found here