Albert Barnes Commentary Joshua 19:34

"and the border turned westward to Aznoth-tabor, and went out from thence to Hukkok; and it reached to Zebulun on the south, and reached to Asher on the west, and to Judah at the Jordan toward the sunrising." — Joshua 19:34 (ASV)

Aznoth-tabor - This place (“ears of Tabor”) was no doubt in the neighborhood of Mount Tabor - probably on the eastern slope; and Hukkok on the western slope.

To Judah upon Jordan - that is, to the “Havoth-jair” (Numbers 32:41), which were on the opposite side of the Jordan. Jair, from whom these towns or villages were named, traced his ancestry in the male line through Hezron to Judah (Numbers 27:1). It is likely that he was assisted by large numbers of his kinsmen of that tribe in his rapid conquest of Bashan.

Hence, the Havoth-jair were, in all likelihood, largely colonized by Judahites, especially perhaps that portion of them nearest the Jordan. Thus, that part of the river and its valley adjacent to these settlements was spoken of as “Judah upon Jordan,” or more literally “Judah of the Jordan” .