Soy sauce is found in the majority of food cultures in Southeast Asia. It is known by a variety of names, including jiàng yóu (China), shōyu (Japan), and ganjang (Korea).
The tradition of fermenting soybeans to make soy sauce probably arose in China, possibly at least 2,500 years ago. The spread of this practice is thought to have been driven by the necessity to limit the use of salt, which was expensive. Soy sauce could easily be used to add both savory and salty tastes to otherwise bland foods, such as cooked rice.