As the title says, have a country which is majority speaking slavic (No matter if it is an existing language or a "parallel" one), in:
1)Basic goal: Inside any place of OTL germany outside alps and the rhine
2)Acceptable goal: Inside the rhine or the alps in germany, switzerland, austria and northern italy
3)Decent goal: anywhere OTL France, northern spain (Catalonia, Aragón, lets just exclude euskadi)
4)Hard goal: anywhere on the iberian peninsula
5)Impossible goal: On the british isles
To achieve said goal any point of divergence is permitted but the challenge has an extra if the modern day result is the most similar to otl...