“She bore to him Zimran and Jokshan and Medan and Midian and Ishbak and Shuah. Jokshan became the father of Sheba and Dedan. And the sons of Dedan were Asshurim and Letushim and Leummim. The sons of Midian were Ephah and Epher and Hanoch and Abida and Eldaah. All these were the sons of Keturah” Gen. 25:2-4
Abraham and Keturah had six children together, most notable of which is Midian. The land of Midian and the Midianites are mentioned many times in scripture. Jethro, Moses father-in-law, was a Priest of Midian. There is some speculation about whether this son of Keturah is connected with the Midianite people, but the general belief is that Midian is the origin. If this is the case, both Moses and his wife Zipporah are from Abrahamic descent – Moses through Isaac, and Zipporah through Keturah.
The sons of Dedan as mentioned are likely not their names, but the names of the peoples that came from them: Asshurim and Letushim and Leummim, probably had names like Asshur, Letush and Leum, or similar.