History & CultureMental model
One detail in the wrong era exposes any forgery.
An anachronism is an object, word or custom that did not yet exist in the depicted period. Renaissance painters show biblical scenes in contemporary dress because they knew no better. Forgers make the same mistake involuntarily – which makes hunting anachronisms one of the sharpest checking tools historians have.
Useful: Ask of any find: did this word, material or concept even exist back then?
Source: en.wikipedia.org