LETUSHIM lĭ too’ shəm (לְטוּשִׁ֖ים). A people descended from Dedan. Others mentioned as being likewise descended from him are the Asshurim and Leummim (Gen 25:3). None of these tribes has been identified, but it is thought that they may have lived in the Sinai Peninsula.

International Standard Bible Encyclopedia (1915)

le-too’-shim, le-tu’-shim (leTushim): A Dedanite tribe in North Arabia (Ge 25:3). With it are connected the ASSHURIM and LEUMMIM (which see).