Overpopulation most likely. In Scandinavian society, I believe the eldest son inherited everything, and the younger sons were left to fend for themselves, but there might have been other reasons as to why the Normans relocated.
The Baltic Sea for Sweden and Finland. The North Sea for Norway.
Because Nadia isn't there
Scandinavia consists of Denmark, Norway and Sweden. Denmark shares a land border with Germany, so technically, no sea separates Scandinavia from the rest of Europe. The main seas around the Scandinavian countries are the Gulf of Botnia, Baltic Sea, Kattegat, Skagerrak, North Sea and Norwegian Sea.
So they can have peace.
There are many parts of Europe which are separated from the rest of the European continent. The main parts are: The British Isles (UK, Ireland, Isle of Man) Scandinavia (Norway, Sweden, Finland and Iceland - Denmark is connected directly to the main land mass) islands like Cyprus, Malta, Greek islands
Jutland forms the mainland of Denmark. It is the peninsula in Northern Europe that stretches in the direction of the rest of Scandinavia.
The Alps separate the country of Italy from the rest of Europe.
The Alps separate Russia from the rest of Europe.
The Finnish airline Blue 1, a subsidiary of SAS Group, flies to around 20 different destinations in Finland, Scandinavia and the rest of Europe. Its head office is located in Helsinki, Finland.
The Pyrenees separate both Spain and Portugal from the rest of Europe.
In Norway you say "skinner sterkt" (shinnar starkt) , and it's similair for the rest of Scandinavia.
Italy is separated from the rest of Europe by the Alps.