It involves a white bear that offers to take the youngest child to fix a family's poor situation. They accept and the bear takes the young girl to a castle where a man slept in the same room as her at night in the dark. As such, she could not see who it was. When she was homesick she was allowed to go home with one condition: She is not allowed to stay with her mother alone. Of course, the young girl doesn't listen and takes a magical candle from her mother. When she returned to the castle, she was able to see the face of the man that has been visiting her bed at night — who was actually the bear. After a what have you done moment he gets taken away by his troll stepmother to marry a troll princess. Before leaving, he tells her that he will be at a land East of the Sun and West of the Moon.
She sets off to find him and meets a woman and her daughter on the way. This woman gives her a golden apple and lets her borrow a horse. Next, she meets a woman who gives her a golden carding comb. A third woman gives her a golden spinning wheel and tells her that she should go find the east wind who might take her to the place that she seeks. The east wind could not help her as he never blew that far so he tells her to visit the west. After facing the same scenario, she visits the south and finally the north wind. The girl then gives up all of her golden items to the princess in exchange for a night with the prince. On the first two nights, she could not wake him. Eventually the servants tell the prince about the girl and he tosses away the drink — actually sleeping potion — from the princess that night. In the end, the girl defeats the trolls (the stepmother and the princess) by washing out the tallow of one of the prince's shirts, because the prince refuses to marry someone unable to do something so simple. The story ends with all the trolls exploding. Everyone lives happily ever after.
It's Aarne-Thompson type 425A, the search for the lost husband, a type of which there are many variants. Compare The Feather of Finist the Falcon and Pintosmalto, and for the Gender Flip Soria Moria Castle and The Blue Mountains.
The tale, with all related versions, is reckoned to be related to the tale of Amor and Psyche, as re-told in the book The Golden Ass by the author Apuleius, from the Roman era. This version is probably the Ur-Example of the story. As everyone will understand, the girl has the role of Psyche, while the prince has the role of Amor.
For a modern novel version, see East by Edith Pattou or Once Upon a Winters Night by Dennis L. McKiernan. There is also one that adds in some Inuit legends into the mix called ICE by Sarah Beth Durst.
A number of famous illustrated versions of this fairy tale have been published, including by Mercer Mayer, among others. All of the versions are slightly different. Do not confuse with the Haruki Murakami book South of the Border, West of the Sun.
Tropes in East of the Sun and West of the Moon:
- Animorphism / Involuntary Shapeshifting: The result of a Curse placed upon the prince by his Wicked Stepmother.
- Beast and Beauty: For a while.
- Big Fancy Castle: Where the bear takes her.
- Color-Coded for Your Convenience: In this and many of the story variations, the groom's animal form is often white. This ties into the cross-cultural concept that white animals are believed to have magical properties.
- Curse Escape Clause
- Disproportionate Retribution: Poor girl makes one mistake, then must trek all over Scandinavia to right it.
- Dogged Nice Guy: The groom, who is always described as treating his bride extremely well when they get to his palace—servants to tend to her every need, great food, etc. This is a strange variant in that he already has the girl; she's just repulsed by his animal appearance.
- Earn Your Happy Ending: And how!
- If I Can't Have You...: The groom is cursed because he won't marry another princess, who is unpleasant and often hideous.
- Involuntary Shapeshifting
- It Was a Gift
- Nice Job Breaking It, Hero!: While it's understandable that the bride's parents would feel Squicked that she's married a bear/wolf/some other huge and intimidating animal, they often have an iron grip on that Idiot Ball when the bride herself isn't carrying it.
- The Quest: The wife has to search for her husband by going east of the sun and west of the moon. This may or may not be an allegory for finding a nonexistent place through The Power of Love.
- Textile Work Is Feminine: The final thing she had to do was wash his shirt clean.
- Villainesses Want Heroes: The troll bride.
- What Beautiful Eyes!: The prince nearly always has gorgeous blue eyes, yet rarely is his hair color even mentioned, which is possibly so he doesn't outshine his wife in the looks department.
- Wicked Stepmother
- Youngest Child Wins: The bride is the youngest child in a very large and poor family.