Why didn’t Korean and Japanese cuisines develop rice noodles?
Rice noodles are a staple in the rice-heavy regions of southern China and mainland Southeast Asia—Vietnam, Thailand, and Myanmar—as well as maritime Southeast Asia, such as Malaysia, Indonesia, and Singapore (although it’s mostly southern Chinese immigrant dishes in those three).
Japan and Korea have also consumed rice heavily for centuries, yet neither developed a tradition of rice noodles. Some people might argue this is due to limited use of rice flour, but Korean rice cakes (tteok) are made from rice flour, showing the ingredient itself was clearly available.