Gascony

From Old French Gascoigne, from Medieval Latin Gasconia, from Vulgar Latin Wasconia, from Latin Vasconia, from Vascones + -ia, from Ancient Greek Οὐάσκωνες (Ouáskōnes) attested in Strabo's 1st-century Geographica, Book III, variously derived from αἴξ (aíx, “goat”) (literally “he-goat people”) or a variant of Ausci (perhaps related to Euskara). Cognate with Basque, Gascon, and Vascon. Equivalent to Gascon + -y.
For sound changes: /w/ → /v/ occurred in the change from Latin to Proto-Romance, while /w/ → /g/ (in loan words starting with /w/) common in (non-Iberian) Romance languages, notably French; compare warranty and guarantee, William and Guillaume. By contrast, /v/ developed into /b/ and /β̞/ in Spanish and Gascon (Spanish Vasco, /ˈbasko/), hence the divergence.