Arendelle is a small nation located on the southernmost point of a great snowy peninsula. Its leader is Queen Elsa, a young monarch gifted with powers over ice and snow. Her second-in-command is her sister, Princess Anna, a fun-loving girl who loves to go on exiting adventures. Arendelle remained a secret to the world for a long time because of its small size and isolationist idealology. That changed on June 7th, 2020, when Queen Elsa came into power, after (accidentally) casting an Eternal Winter upon the world. Soon, however, she ended it with the help of Anna and her new friends. Arendelle remained locked in a Victorian-era culture due to its ceasing contact with the outside world almost completely in 1845 and maintaining a traditional Monarchy for almost 175 years -- so isolated, even the combined efforts of all the world's spy agencies (including the KND and S.H.I.E.L.D.) couldn't find it.
When Fuse invaded, Arendelle was locked in a bloody conflict with the Southern Isles and Weselton following two assassination attempts upon Elsa and Anna. However, when Fuse destroyed the Southern Isles and Weselton in one of his devastating surprise attacks upon the East, Queen Elsa and Princess Anna transported themselves to the FusionFall universe and were immediately escorted by S.H.I.E.L.D. to the small town of Gravity Falls to hide from Fuse.