I can't buy the Siege of Paris, it's a DLC, because I had the opportunity to sell the game first.

River sackings are a side quest, but they are a great chance to get some great armor and brutal sword early on game, and the best resources to quickly improve your Viking settlement.

In horizon the key is to mount the beasts, you must complete the cauldrons to be able to control more types of beasts and be able to mount them, and then you do the fast trips through the bonfires.