From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

ASSHURIM . The Asshurim, Letushim, LeummimGenesis 25:3 ) were Arabian tribes, supposed to be descended from Abraham and Keturah through Dedan. By the Asshurim the Targum understood dwellers in encampments to be meant. A tribe A’shur appears on two Minæan inscriptions.

J. Taylor.

Morrish Bible Dictionary [2]

Sons of Dedan.  Genesis 25:3 .

International Standard Bible Encyclopedia [3]

a - shoo´rim ( אשׁוּרים , 'ashshūrı̄m ): Mentioned among the sons of Dedan, son of Jokshah, son of Abraham by Keturah ( Genesis 25:3 ).