The Fuyu languages or Buyeo languages are a hypothetical language family that would relate the languages of Fuyu, Goguryeo, Baekje and the Japonic languages, and possibly place them together as a family under the hypothetical Altaic family. Limited linguistic evidence links two of these languages—Goguryeo and Japonic—but a link to the others is based almost entirely on historical evidence without significant attested linguistic evidence. In particular, Goguryeo and Baekje asserted themselves to be descended from Fuyu, and both traditionally had close relations and kinship with Yamato Japan until they ultimately fell to the kingdom of Silla.

The Fuyu languages hypothesis does not include the language of Silla, considered to be the ancestor of the modern Korean language, but many supporters of the Altaic theory include Korean as an Altaic language as well. Some scholars have proposed the hypothetical language family of Han languages that includes the languages spoken in Byeonhan, Mahan, and Jinhan, the proto-states known collectively as the Samhan that preceded Silla, Baekje, and Gaya in Southern Korea. According to this theory, the language of Silla and the lower stratum of Baekje language are Han languages. The nature of Korean's relationship with the Japonic languages, let alone with the hypothetical Fuyu and Han languages, remains controversial and subject to considerable debate and speculation.

See also

• List of Korea-related topics