In medieval ethnography, the world was believed to have been divided into three large-scale racial groupings, corresponding to the three classical continents: the Semitic peoples of Asia, the Hamitic peoples of Africa and the Japhetic peoples of Europe.
It is written in Genesis: "The sons of Japheth: Gomer, and Magog, and Madai, and Javan, and Tubal, and Meshech, and Tiras. and the sons of Gomer: Ashkenaz, and Riphath, and Togarmah. And the sons of Javan: Elishah, and Tarshish, Kittim, and Dodanim. By these were the Isles of the Gentile divided in their lands everyone after his tongue, after their families, in their nations." (Gen 10:2-5)
In the Bible, Japheth is ascribed seven sons and seven named grandsons:
The intended ethnic identity of these 'descendants of Japheth' is not certain; however, over history, they have been identified by Biblical scholars with various historical nations who were deemed to be descendants of Japheth and his sons — a practice dating back at least to the classical encounters of Jew with Hellene, for example in Josephus's Antiquities of the Jews, I.VI.122 (Whiston). Josephus wrote:
Japhet, the son of Noah, had seven sons: they inhabited so, that, beginning at the mountains Taurus and Amanus, they proceeded along Asia, as far as the river Tanais (Don), and along Europe to Cadiz; and settling themselves on the lands which they light upon, which none had inhabited before, they called the nations by their own names.
Josephus detailed the nations supposed to have descended from the seven sons of Japheth.
Ancient and medieval ethnography
An ancient, relatively obscure text known as Pseudo-Philo and thought to have been originally written ca. 70 AD, contains an expanded genealogy that is seemingly garbled from that of Genesis, and also different from the much later one found in Jasher:
Sons of Japheth: "Gomer, Magog, and Madai, Nidiazech, Tubal, Mocteras, Cenez, Riphath, and Thogorma, Elisa, Dessin, Cethin, Tudant."
Sons of Gomer: Thelez, Lud, Deberlet.
Sons of Magog: Cesse, Thipha, Pharuta, Ammiel, Phimei, Goloza, Samanach.
Sons of Duden: Sallus, Phelucta Phallita.
Sons of Tubal: Phanatonova, Eteva.
Sons of Tyras: Maac, Tabel, Ballana, Samplameac, Elaz.
Sons of Mellech: Amboradat, Urach, Bosara.
Sons of Ascenez: Jubal, Zaraddana, Anac.
Sons of Heri: Phuddet, Doad, Dephadzeat, Enoc.
Sons of Togorma: Abiud, Saphath, Asapli, Zepthir.
Sons of Elisa: Etzaac, Zenez, Mastisa, Rira.
Sons of Zepti: Macziel, Temna, Aela, Phinon.
Sons of Tessis: Meccul, Loon, Zelataban.
Sons of Duodennin: Itheb, Beath, Phenech.
Among the nations that various later writers (including Jerome and Isidore of Seville, as well as other traditional accounts) have attempted to assign to them, are as follows:
Tiras (sons were Benib, Gera, Lupirion and Gilak)
The term Caucasian as a racial label for Europeans derives in part from the assumption that the tribe of Japheth developed its distinctive racial characteristics in the Caucasus area, having migrated there from Mount Ararat before populating Europe. In the same vein, Georgian nationalist histories associated Japheth's sons with certain ancient tribes of the Caucasus area, called Tubals (Tabals, Tibarenoi in Greek) and Meshechs (Meshekhs/Mosokhs, Moschoi in Greek), who they claimed represented ancient pre-Indo-European and non-Semitic, possibly "Proto-Iberian", tribes of Asia Minor of the 3rd-1st millennia BC. This theory influenced the use of the term Japhetic in the linguistic theories of Nikolai Marr (see below).
During the eighteenth and nineteenth centuries, the Biblical statement attributed to Noah that "God shall enlarge Japheth" (Genesis 9:27) was used by some preachers  as a justification for the "enlargement" of European territories through imperialism, which they interpreted as part of God's plan for the world. The subjugation of Africans was similarly justified by the curse of Ham.
The term was used in a different sense by the Soviet linguist Nicholas Marr, in his Japhetic theory, which was intended to demonstrate that the languages of the Caucasus formed part of a once-widespread pre-Indo-European language group.