The Tarbelli were an Aquitani pre-Roman tribe settled in what today is southwestern France, in the region between the river Adour and the Pyrenees. The capital of the Tarbelli people was Aquae Tarbellicae, present-day Dax. They were the ancient inhabitants of Labourd, in the Northern Basque Country, in the present-day French department of the Pyrénées-Atlantiques.
Their historical territory today corresponds very well with the extension of the Lapurdian dialect of the Basque language. The Tarbelli, like all other Aquitanians, spoke an archaic form of the Basque language, known as Aquitanian language, whose dialects are unknown.
The Tarbelli are mentioned by Roman authors; Julius Caesar names them Tarbelli quatuorsignani, "Tarbelli of the four banners", which means the Tarbelli were actually a confederacy of four different tribes. They lived in small territory in what today is the southwest of France, between the river Adour and the Pyrenees, this region being the traditional province of Labourd, of the Northern Basque Country.
Their capital city was Aquae Tarbellicae, present-day Dax, with Orthez being also an important Tarbelli city. They are presumably related to other Aquitani tribes, as the Vascones, among others. During the Roman times, the Tarbelli territory was part of a greater region called Novempopulania.