Soy sauce and tamari originated in Japan as by-products of miso. In fact, tamari was traditionally made from the liquid left in the bottom of the barrels used during the fermentation of miso. Then if more pressure was applied to the fermentation mixture more liquid could be obtained. Because it is both tasty and appetising more than is needed is often consumed. It shouldn't be consumed uncooked because it's very salty and it makes you thirsty, constricts digestion and can even stimulate sweet cravings and hence hypoglycaemia. It should always be consumed in small quantities.