I was browsing wikipedia the other day getting ready for the new season of Vikings and saw that the character Rollo was was based on the great great great(however many generations) grand dad of the royal family in England.
This seems like a pretty amazing family line that has documentation to back it up, are there any longer ones?
It seems the answer is probably either modern day descendants of Confucius or the Japanese imperial family (having long existing royalty is a good way to have documented lineage). either way the answer seems to lie in east asia