What is "busturialdea"

Busturialdea, also named Busturialde - Urdaibai is a comarca of the province of Biscay, in the Basque Country, Spain. It is the heir of "Busturia", one of the original merindades that used to compose the province of Biscay, which should not be confused with Busturia, which is a municipality located in this region. Busturialdea is a diminished portion of the same original subregion and has two capital cities; Bermeo and Gernika-Lumo. It is one of the seven comarcas that compose the province of Biscay.