This is further than any Viking has ever gone before, as Bjorn says. The people living there are Mussulman, as Rollo and the Europeans from that age call them. The name evolved in English to Muhammadan, Moslem, and today, Muslim.
Rollo also knows that these people worship Allah. Floki soon discovers Allah is a God without a picture, statue, or representation. The pagan Vikings have now encountered not only Christians in their voyages but Muslims.
The Vikings can't help being the plunderers they are. They're delighted with the food, and even more so the harem. Rollo is an interesting, potentially pivotal character here. He's renounced the pagan faith, and the Viking way of life, to live as royalty with his wife and family in France. He's caught up in the traditional Viking way now, but my guess is at some point he'll snap out of it.
The key here, and in the overall story of the the Vikings now, is which approach to strange lands will they take? Ragnar's in England in didn't work out so well. Rollo's in France was much better for him - though not completely satisfying, which is why he went on this mission.
Meanwhile, back in Norway, as they're now calling it, Lagertha is told she'll be killed by a son of Ragnar. The only thing we can know with confidence about this is that the killer won't be Bjorn - because Lagertha is his mother. Otherwise ... well, the death of Ragnar shows we need to take the possibility of the death of major characters more seriously. And that includes Lagertha.
But speaking of death - I don't know, but I wouldn't be totally stunned if we encountered Ragnar wandering around somewhere in England at some point in the future. I wouldn't bet on it, but ... you just never know, when you don't see the character's head literally cut off ...
See also Vikings 4.1: I'll Still Take Paris ... Vikings 4.2: Sacred Texts ...Vikings 4.4: Speaking the Language ... Vikings 4.5: Knives ... Vikings 4.8: Ships Up Cliff ... Vikings 4.10: "God Bless Paris" ... Vikings 4.11: Ragnar's Sons ... Vikings 4.12: Two Expeditions ... Vikings 4.13: Family ... Vikings 4.14: Penultimate Ragnar? ... Vikings 4.15: Close of an Era
And see also Vikings 3.1. Fighting and Farming ... Vikings 3.2: Leonard Nimoy ...Vikings 3.3: We'll Always Have Paris ... Vikings 3.4: They Call Me the Wanderer ... Vikings 3.5: Massacre ... Vikings 3.6: Athelstan and Floki ...Vikings 3.7: At the Gates ... Vikings 3.8: Battle for Paris ... Vikings 3.9: The Conquered ... Vikings Season 3 Finale: Normandy
And see also Vikings 2.1-2: Upping the Ante of Conquest ... Vikings 2.4: Wise King ... Vikings 2.5: Caught in the Middle ... Vikings 2.6: The Guardians ...Vikings 2.7: Volatile Mix ... Vikings 2.8: Great Post-Apocalyptic Narrative ... Vikings Season 2 Finale: Satisfying, Surprising, Superb
And see also Vikings ... Vikings 1.2: Lindisfarne ... Vikings 1.3: The Priest ... Vikings 1.4: Twist and Testudo ... Vikings 1.5: Freud and Family ... Vikings 1.7: Religion and Battle ... Vikings 1.8: Sacrifice
... Vikings Season 1 Finale: Below the Ash
historical science fiction - a little further back in time