Galicia is quite mountainous, a fact which has contributed to isolate the rural areas, hampering communications, most notably in the inland. The main mountain range is the Macizo Galaico (Serra do Eixe, Serra da Lastra, Serra do Courel), also known as Macizo Galaico-Leonés, located in the eastern parts, bordering with Castile and León. Noteworthy mountain ranges are O Xistral (northern Lugo), the Serra dos Ancares (on the border with León and Asturias), O Courel (on the border with León), O Eixe (the border between Ourense and Zamora), Serra de Queixa (in the center of Ourense province), O Faro (the border between Lugo and Pontevedra), Cova da Serpe (border of Lugo and A Coruña), Montemaior (A Coruña), Montes do Testeiro, Serra do Suído, and Faro de Avión (between Pontevedra and Ourense); and, to the south, A Peneda, O Xurés and O Larouco, all on the border of Ourense and Portugal.

What is Galicia's main mountain range?