Wikipedia
Jokshan ("an offense", "hardness", or "a knocking"); most probably Josephus' Jazar. According to the Bible he was the second son of Abraham and his either wife or concubine Keturah, whom he wed after the death of Sarah. Jokshan had five other brothers: Zimran, Medan, Midian, Ishbak and Shuah; as well as two half brothers: Ishmael and Isaac.
Josephus records that "Abraham contrived to settle them in colonies; and they took possession of Troglodytis and the country of Arabia the Happy, as far as it reaches to the Red Sea." Abraham in all probability, tried to keep them apart from Isaac to avoid conflict while fulfilling God's commission to spread out and inhabit the globe.
Jokshan became the father of Sheba and Dedan. Dedan had three sons, named Asshurim, Letushim, and Leummim.