Complex sentence: It is said to be that Gochujang is unique ingredient only in Korea; even though China and Japan are the countries where Korea has historically and culturally been influenced, none of them use Gochujang for their traditional cuisines.
Split into simpler sentences: It is said to be that Gochujang is unique ingredient only in Korea. Even though China and Japan are the countries where Korea has historically and culturally been influenced, any of these countries do not use Gochujang for its traditional cuisines.