John Calvin Commentary Jeremiah 25:23

"Dedan, and Tema, and Buz, and all that have the corners [of their hair] cut off;" — Jeremiah 25:23 (ASV)

I will now only briefly touch on the extreme ones in a corner, or those bounded by a corner, who were almost unknown to the Jews because of their distance. After speaking of such remote nations, to avoid being tedious through excessive length, he mentions all the extreme ones in a corner, that is, those who were bounded by the farthest limits.

As for Dedan, Tema, and Buz, we know that these countries derived their names from their founders. We learn from Moses who Dedan was, and also who Tema and Buz were (Genesis 25:3, 15; 1 Chronicles 5:14). Two of them were descendants of Abraham by Keturah.

There is no need to say more about these countries, for they are not known to us today, and we cannot learn the extent of any of these countries from geographers. For there was hardly a place, at the time when pagan writers began their records, that had not changed its name long before. We conclude, however, that these were eastern countries.