Warning: Contains SPOILERS for Vikings: Valhalla season 1.
Netflix's Vikings: Valhalla season 1 runs into some of the confusing timeline issues that hurt much of Game of Thrones seasons 7 and 8. Vikings: Valhalla takes place 100 years after Vikings, the show it spins off from, although exactly when it's set is more open to debate. Valhalla is inspired by true stories and historical events, but it also takes a lot of liberties with its timeline, bringing together characters and actions that wouldn't have necessarily overlapped.
Still, for the most part, Vikings: Valhalla's timeline works to its advantage. There's no real pretence of being completely historically accurate here, and so having the St. Brice's Day Massacre (which took place in 1002) followed by Canute's invasion of England (he didn't become King of England until 1016), in a time period only supposed to be 100 years after Vikings (which ended in 800s), doesn't cause big problems.
Related: Vikings: Valhalla True Story — Every Major Change To Real Life History
Instead, Vikings: Valhalla's timeline issues come from the more micro details, specifically in how events are portrayed as taking place and how long they're supposed to last. There is, for instance, a gap of a year between the St. Brice's Day Massacre and Canute heading out for revenge; there's a lot of sailing between Norway and England, multiple battles are waged, and there's an entire regime change in England followed by Jarl Kåre's Beserkers and Jarl Olaf teaming up to take Kattegat by the end, but without a complete sense of how much time is passing. There are a couple of solid identifies that mean Leif Eriksson et al were away for several months, but the condensed nature of its historical timeline
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