In Assassin's Creed Valhalla, you may come across Rigsogur Fragments, which are a type of collectibles in the game. On this page of the guide, you will learn where to find the collectible and how to reach it. This will make it easier for you to max out the Oxenefordscire region.
The fifth page of the saga is located east of Oxenefordscire.
The fragment is located on a boat worked on by a man who has a side mission for you. He will have no problem with you taking this item.