A saga is a medieval Icelandic or Norse prose narrative of achievements and events in the history of a personage, family, etc.
or
Any narrative or legend of heroic exploits.
It's out of ancient sea lore from Norse mythology and sagas.
Norse mythology took a long time in the making and cannot be pinned down to a single book, verse, author or year. Most of the Eddas & Sagas that became the mythology, however, were written in Iceland in the 12th to 13th centuries.
Sagas
The chief god of Norse mythology is Odin.
Norse Mythology originated in early Scandinavia.
Norse mythology, or you can also say the myths of Scandinavia.
Norse mythology's chief god was odin.
the word 'Norse' would be capitalised, but not 'mythology'.
Norse mythology comes from early Scandinavia.
Asgard is the home of the gods in Norse Mythology.
Some call it the Norse Religion, Viking Mythology, and the Viking Religion, but the most correct is Norse Mythology.
Amazon.com has a wide selection of books on Norse Mythology.