That the modern handshake dates back to the 5th century BC. It originated from swordsman greeting each other with their weapon hand free, showing no sign to fight.
The first handshake on human history is documented by the monument of Kalhu, showing the Assyrian king Shalmaneser III and Marduk-zakir-šumi I of Babylon shaking hands in a public display of Assyro-Babylonian friendship. Archaeological ruins and ancient texts show that handshaking was practiced in ancient Greece as far back as the 5th century BC; a depiction of two soldiers shaking hands can be found on part of a 5th-century BC funerary stele on display in the Pergamon Museum, Berlin (stele SK1708) and other funerary steles like the one of the 4th century BC which depicts Thraseas and his wife Euandria handshaking (see images on the right). The handshake is thought by some to have originated as a gesture of peace by demonstrating that the hand holds no weapon.