I had (still have but likely wont ever get around to write it) a setting (as I wanted to write a story) in mind that involved a much more successful muslim conquest - or more precisly a second wave of muslim conquest in the 900's - OTL they did conquer a bit at this time but were mostly raiding.
1. My first POD was that Constantinople falls to the arabs in 719. Thus eliminating the ERE as a guard of Europe against muslim forces from the east.
2. In the 900's Italy and most of France falls to the muslims.
3. This events sends a lot of refugees to the surviving christian countries - who have a hard time accomodating them.
4. The norse discovery of Vinland is taken up as a possible solution: a lot of the refugees are sent to the new world - where they will be safe from the conquering muslims.
5. A lot of the first arrivals die but ultimately new medieval christians statelets are established in the Americas. They are mostly French and Italians (I have the greek refugees ground a New Constantinople around OTL Detroit).
6. By the 1400's the Europeans have comfortably settled everything east of the Appalachian Mountains and the Great Lakes and are settling the area east of the Mississippi. However Native states have grown strong enough to seriously hinder them (though christians natives are accepted and threated no different than the europeans). The Europeans are nominally under one Emperor but in practice the various duchies, cities etc are very Independent - HRE like. The one thing they group together to do is opposing the natives and furthering the conqests.
7. Its in the mid 1400's that the Crusades are called (earlier calls would have been futile) - for the reconquest of Europe. The call is taken up and the 1st crusade succeeds in driving the muslims from France. (I havent gone further as my story would have been set there)
1. My first POD was that Constantinople falls to the arabs in 719. Thus eliminating the ERE as a guard of Europe against muslim forces from the east.
2. In the 900's Italy and most of France falls to the muslims.
3. This events sends a lot of refugees to the surviving christian countries - who have a hard time accomodating them.
4. The norse discovery of Vinland is taken up as a possible solution: a lot of the refugees are sent to the new world - where they will be safe from the conquering muslims.
5. A lot of the first arrivals die but ultimately new medieval christians statelets are established in the Americas. They are mostly French and Italians (I have the greek refugees ground a New Constantinople around OTL Detroit).
6. By the 1400's the Europeans have comfortably settled everything east of the Appalachian Mountains and the Great Lakes and are settling the area east of the Mississippi. However Native states have grown strong enough to seriously hinder them (though christians natives are accepted and threated no different than the europeans). The Europeans are nominally under one Emperor but in practice the various duchies, cities etc are very Independent - HRE like. The one thing they group together to do is opposing the natives and furthering the conqests.
7. Its in the mid 1400's that the Crusades are called (earlier calls would have been futile) - for the reconquest of Europe. The call is taken up and the 1st crusade succeeds in driving the muslims from France. (I havent gone further as my story would have been set there)