When does Vikings: Valhalla take place? The real history behind the Netflix show

gamesradar.com:

Unless you are a history buff, the Vikings: Valhalla timeline may as well be Norse code. That can be frustrating. Chances are, you will want to immediately dive into that corner of history after bingeing Netflix’s swords-and-shield epic featuring real-life historical figures such as King Canute, Leif Eriksson, and the Earl of Godwin.

But where to start? At the expense of thumbing through history books and reams of confusing Wikipedia entries, we’re here to bring you a brief overview of the period that newcomers can use to provide further context to the series. On top of that, Valhalla diehards can even use the info to accompany them on a rewatch. We’ll even keep things as spoiler-free as possible.

Vikings: Valhalla begins in the early 11th Century. 1002 to be precise. To be even more precise, the premiere is set on November 13, 1002, when the St Brice’s Day Massacre took place. The events of the series, though, take place some time later.

Sadly for those looking to follow along with a proper timeline, Vikings: Valhalla plays it pretty fast and loose with which year everything is set in. 

The only thing that is clear is that a fair amount of time has passed since St Brice’s Day. The premiere’s story card reveals Canute’s plans to sail for England in “revenge”, but comes without a firm date.

There are other historical moments that did not happen in the order presented in the Netflix series, which confuses things further. King Canute’s rise to power comes almost 15 years after St Brice’s Day, for example. There’s also the small matter of Harald not even being born in 1002, despite being present during the St Brice’s Day Massacre. As such, it’s a fool’s errand attempting to piece everything together and place the series