Many people think handshaking is a modern way of welcoming, wishing, or dealing. But handshake was coming from very late history.

Archeologists found many old stuff like paintings, sculptures of people shaking hands

Hence we mentioned it was from history, it was invented in the times of Kings.

Past then people used to carry swords, they are tied in the left side of a person, so that he can easily pull it out with his right hand when needed.

Since the sword is always with them, they thought it's better to shake his right hand with another person's right hand to show that they are not going to attack him, since my hand is with you.