Basque dialects are linguistic varieties of the Basque language which differ in pronunciation, vocabulary and grammar from each other and from Standard Basque. Between six[1] and nine[2] Basque dialects have been historically distinguished:
In modern times, however, both Lower Navarrese and Lapurdian are considered part of a Navarrese–Lapurdian dialect, so there would be five dialects, divided into 11 subdialects and 24 minor varieties.[3]
The boundaries of all these dialects do not coincide directly with current political or administrative boundaries. It was believed that the dialect boundaries between Bizkaian, Gipuzkoan and Upper Navarrese showed some relation to some pre-Roman tribal boundaries between the Caristii, Varduli and Vascones. However, main Basque dialectologists now deny any direct relation between those tribes and Basque dialects. It seems that these dialects were created in the Middle Ages from a previously quite unified Basque language, and the dialects diverged from each other since then as a result of the administrative and political division that happened in the Basque Country.[3][4]