Uncertain. The word is used in the expressions Mal e arbën meaning "mountains and fields", and Shkojm ne Arbëni "to climb down the mountain, to go in the plain land", thus connecting the word with an original form *arb, related to Proto-Indo-European*arH- 'to plow' and *h₂rh₃ 'arable land', or 'plain land' (cf. Latin Latium from latus 'wide, plain', and arvum(“corn-field”), Ancient Greek ἄρουρα(ároura, “arable land”)) or to Germanic *arbaz (cf. Old Norse arfr(“inheritance”)), Old Irish orbe 'id', Latin orbus(“bereaved, parentless”), Slavic *orbь(“slave”). The term represents the name of a south Illyrian tribe attested in Ancient Greek (Ancient GreekἈλβανοί(Albanoí)), later on denoting a proper name for an ethnic Albanian until (around) the eighteen century when it was replaced with shqiptar (see shqip).