Ishbak was one of the six sons born to Abraham by Keturah, whom Abraham married after Sarah's death. Like his brothers, Ishbak received gifts from Abraham and was sent away eastward, away from Isaac. His descendants likely settled in Arabia.
1.John McClintock and James Strong, "Ishbak," in Cyclopedia of Biblical, Theological and Ecclesiastical Literature, vol. IV (Harper & Brothers, 1867–1887).