The Vikings were all Scandinavian but not all Scandinavians were Vikings.
Story behind the song
The Vikings were diverse Scandinavian seafarers from Norway, Sweden, and Denmark whose raids and subsequent settlements significantly impacted the cultures of Europe and were felt as far as the Mediterranean regions c. 790 - c. 1100 CE.
The Vikings were all Scandinavian but not all Scandinavians were Vikings.
The term Viking applied only to those who took to the sea for the purpose of acquiring wealth by raiding in other lands, and the word was primarily used by the English writers, not inclusively by other cultures.
Most Scandinavians were not Vikings, and those who traded with other cultures were known as Northmen, Norsemen, or other terms designating their origin.
At the centre of the Viking universe was Yggdrasill,
a gigantic ash tree with three roots:
1 in Asgard the land of the gods (the Aesir);
2 in Jotunheim the land of the frost giants;
3 in Niflheim the world of the dead.
Near these roots are three wells:
1 Hvergelmir,
in which Nidhogg lived
The serpent that gnawed at the trees roots;
2 Mímisbrunnr, the source of wisdom
Odin sacrificed an eye for its waters;
3 Urdarbrunnr,
the Well of Fate,
from which the tree is watered by the three Norns or Fates.
Urd,
Verdandi
and Skuld.
The leader of thier gods was Odin,
who married the goddess Frigg.
Below them were lesser deities such as
Thor (god of thunder),
Tyr (god of war),
Loki (god of fire),
Frey and Freya (gods of fertility),
Aegir and Njord (gods of the sea),
Bragi (god of poetry),
Ull (god of archery)
and Hel (goddess of the underworld).