Before the boundaries of the national park were designated, “Snowdonia” was generally used to refer to a smaller area, namely the upland area of northern Gwynedd centred on the Snowdon massif, whereas the national park covers an area more than twice that size extending far to the south into Meirionnydd. This is apparent in books published prior to 1951, such as the classic travelogue Wild Wales by George Borrow (1862) and The Mountains of Snowdonia by H. Carr & G. Lister (1925). F. J. North, as editor of the book Snowdonia (1949), states “When the Committee delineated provisional boundaries, they included areas some distance beyond Snowdonia proper.” The traditional Snowdonia thus includes the ranges of Snowdon and its satellites, the Glyderau, the Carneddau and the Moel Siabod group. It does not include the hills to the south of Maentwrog. As Eryri (see above), this area has a unique place in Welsh history, tradition and culture.
Text taken from wikipedia