The handshake appeared in ancient times as a symbol of a treaty of peace and friendship. For some ancient peoples of India, the handshake was part of the wedding ceremony. Among the ancient Romans, it also bore a ritual character, then passed to Christians, and later became a simple form of greeting.
However, shaking hands is far from the only way to say hello and say goodbye. NM Przhevalsky noted an interesting custom among the Tibetans. When the younger meets and says goodbye to the elder, the first takes off his hat and tilts his head slightly, sticking out his tongue. In our time, lamas, when greeting, show their hands, palms facing the guest, and stick out the tip of their tongues, thereby showing high deference.
In West Africa, they greet each other with strokes of the palms on the chest, and in Central Africa, with a polite bow and clapping, pronouncing the appropriate pleasant words. The Japanese observe the national custom: they bow several times and ask each other about health and well-being.
The greetings of all peoples are worthy of respect, for they express the good feelings of the people.
Medieval knights, to show their peaceful intentions, when they met, took off their helmets and opened their heads, leaving it unprotected. In the future, the removal of the headdress as a sign of greeting took root everywhere. A simplification of this greeting was to put a hand on the headdress, as it were, with the intention of taking it off.