Although The Last Kingdom may feel like a fictional story set in a real world, it wasn’t drawn up out of thin air especially when it comes to Uhtred the Bold. Based on Bernard Cornwall’s series novel series The Saxon Stories, both the books and The Last Kingdom include characters that are based on real-life individuals. However, the story did take some historical liberties along the way. This was partly out of necessity, as there aren’t detailed records from 800 to 1100. Nonetheless, all five seasons of The Last Kingdom make a valiant attempt at putting history onto the small screen.

https://screenrant.com/last-kingdom-things-uthred-accurate-and-arent/