Of unknown location in the form Obron (attested only here). Perhaps a mangled rendering of Hebron in the present-day West Bank -- which Theognostus registers as Obrion.
Additionally/alternatively, ps.-Zonaras and Gennadius Scholarius cite *)/wbrwn [sic] as the name of a river. [No river Obron is known, but there is a river Obrimas in Phrygia (Pliny, Natural History 5.29; cf. one suggested emendation of Livy 38.15.12), and Claudius Ptolemy 2.10.17 has a river Obringas separating Upper and Lower Germany.]