Busturialdea is located at the north of the province of Biscay, limiting with the comarcas of Lea-Artibai on the east, Uribe and Greater Bilbao on the west and Durangaldea on the south.
This development is part of the Durango+ project, which aims to improve the service and frequencies in the Durangaldea region.
The award was ratified in 1179: the left bank of the River Nervión became part of Castile, while the rest of Biscay, Durangaldea and Álava (east from the Bayas River) were to stay with Navarre.