Historic Harald Hårfagre did not live in the same time as Ragnar.
Yidu is introduced as a Chinese woman captured by pirates and sold to the Vikings as a slave.
Chinese trade relations during the Tang dynasty extended west to the Arabian Peninsula, East Africa, and Egypt but it is unlikely that a Chinese woman would have somehow been moved as a slave all the way to Paris and beyond.
Chinese trade relations during the Tang dynasty extended west to the Arabian Peninsula, East Africa, and Egypt but it is unlikely that a Chinese woman would have somehow been moved as a slave all the way to Paris and beyond.
In the hut where Ragnar installs the Chinese slave to make her his mistress, we can see several animals including a python, an animal living in Central Africa. At that time no Western civilization had gone so far in the exploration of the World, and even less the Vikings.
Yidu gives him "Chinese Medicine" which appears to be betel nut which is eaten wrapped in leaves with paste. This can be clearly seen as it turns Ragnar's mouth and saliva red. Ragnar's reaction however, appears to be much stronger than that of betel nut.