

That would make Ragnar either very young attacking Lindisfarne or his sons very old when they invaded with their army 72 years later.

The historical viking attack at Lindisfarne was in 793 and the Great Heathen Army of Ragnar's sons appeared in 865. The timeline is compressed greatly, as seen in the reigns of Aelle and Ecbert. Other stuff in the show is not so accurate. King Aelle, however, reigned several decades later from the mid-860's to his death in 867, reportedly at the hands of Ragnar's sons after their Great Heathen Army took York in 866. King Ecbert was the grandfather of the renowned Alfred the Great and reigned from about 802 to 839. King Ecbert and King Aelle are historical but were not kings at the same time.

Ivar is the same in both, although there is a lot of debate over what the nickname "the boneless" actually meant.

The second eldest named in the show, Ubbe, is one of the leaders of the historical Great Heather Army but doesn't appear in the game. The eldest son, Bjorn, you know is the supposed founder of the Munso dynasty of Sweden. Haldfan in the sagas and the game and the Hvitserk in the show are likely the same person - Hvitserk being named in some sagas and Halfdan in others, but never the two together. The Great Heathen Army was a real event and some of the Ango-Saxon Chronicle and the Historia Regum Anglorum matches up with the sagas, such as the blood eagle being intended for King Aelle as revenge for the killing of Ragnar. As to his sons, whether or not they were actually all his sons is debatable, but they are mostly historical figures. The real person is debatable as to identity: he could be any one of a number of possible historically documented people, including the Horik who appears as King Horik in the show. The show follows some of the information about Ragnar from the sagas.
