"One of the reasons of close economic and cultural relations was the tradition of fraternizing existing in the Caucasian mountains. Tsova-Tushs (Batsbis) and Tushs generally, were often fraternizing not only with other Georgian mountaineers, but also with Kists (Chechens) and Didos (Daghestans).
The appropriate rituals were always followed this tradition. The future blood brothers were dropping silver coin scrapes into a bowl full of milk, than they drank the milk and after that they were considered as, so called - “oath and silver eaten”.
Another form of fraternizing was, when in the same wooden bowl the two men were dripping blood from their cut fingers. There was the other form fraternizing as well. If the candidates’ mothers were alive, they were going to them together and touching mothers’ (each other’s) breasts with their teeth. This ritual was held in the presence of the whole family and the neighbors. The sense of collectivity was characteristic to the mentality of the mountain dwellers. The blood brothers often changed their horses and armament. It was not obligatory, though. "
A very recommended reading: