The validity of documents was marked by fingerprinting in what time period?

 The correct answer is:  In ancient Babylon, fingerprints were pressed on clay tablets to mark contracts. The oldest documents known as such where fingerprints are shown date from China in the third century B.C.  Sir William Herschel began collecting fingerprints in 1856 and noted that they were not altered with age. In 1888 Sir Francis Galton together with Sir Edmund Richard Henry developed the fingerprint classification system and this system is still used in the United States. Identification by fingerprints is very reliable.