Devir is a city of Kohanim in the hills of Yehuda. 

Currently identified as Hirbet Rabud (Y. Aharoni).

As a continuation to the war with the southern kings, it is told that Yehoshua captured Devir (Joshua 10, 30-39; Joshua 12, 13).
Giants were found in Devir in the days of Yehoshua (Joshua 11, 21).
The story of Kalev's conquest and settlement relates that Otniel ben Kenaz captured Devir (Kiryat Sefer) in return for the right to marry Akhsa, Kalev's daughter (Joshua 15, 16-17).