Younger son of Eber and progenitor of thirteen Arabic tribes (Gen. x. 25-29; I Chron. i. 19-23), many of which—as Hazarmaveth, Shebah, Ophir, and Havilah—have been identified. The name seems to mean "the younger" or "the smaller," but in Gen. R. xxxvii. 10 it is interpreted as "he who humbles himself," and for his humility Joktan was rewarded by being made the ancestor of thirteen tribes. The place of settlement of Joktan's descendants is given as "from Mesha, as thou goest unto Sephar, a mount of the east" (Gen. x. 30). The district indicated is in Arabia, but Targum pseudo-Jonathan identifies Sephar with Sepharvaim. Josephus ("Ant." i. 6, § 4) asserts that their dwelling was "from Cophen, an Indian river, and in part of Asia adjoining it."
Joktan in Arabic literature bears the name "Ḳaḥṭan." In Gen. x. Joktan is described as the ancestor of several south-Arabian tribes. In accordance with this statement Arab genealogists hold Ḳaḥṭan to be the first king of Yemen, and his son and successor Ya'rub the first person who spoke Arabic. This is but the legendary form of the tradition that Ḳaḥṭan was the progenitor of the southern Arabs, or Arabs proper, while the Ishmaelite Arabs were originally of non-Arab stock; but, pretending to be Arabs, they adopted Arab customs and intermarried with genuine Arabs, being therefore called "Musta'rabs." Another son of Ḳaḥṭan, who was called Jurhum, emigrated to northwest Arabia, and founded a kingdom in the Ḥijaz. This tradition was probably invented at a later date in order to establish a close relationship between the northern and southern Arabs, because it is added that Ishmael married a woman of the tribe of Jurhum and became a member thereof.