Fifth-century child’s skeleton shows evidence of “vampire burial”

The article speaks about the idea of vampires coming from different cultures all over the world.  My question is where did these ideas come from and how did they develop all over the world?  I could see one region coming up with that idea, but how did the same myth develop in areas that had no contact with each other?

Enlarge / Archaeologists excavated the skeleton from a fifth-century cemetery in the Umbria region of Italy. (credit: David Picked/Stanford University ) Archaeologists have discovered the skeleton of a 10-year-old child at an ancient Roman site in Italy with a rock carefully placed in its mouth.

Source: Fifth-century child’s skeleton shows evidence of “vampire burial”