In Assassin's Creed Valhalla, you can find Offering Altars. On this page of the guide, you will learn where to find the altars. This will make it easier for you to max out the Eurvicscire region.
You will find a Offering Altar east of Jorvik.
To count this side activity you need 5 fabrics. You will get them from chests found in the enemy camp.