sentences:  The Cameroonian Highlands forests extend across the Cameroon Highlands, a chain of extinct volcanoes, covering an area of in eastern Nigeria and western Cameroon.The ecoregion lies above 900 meters elevation, and is surrounded at lower elevations by the Cross-Sanaga-Bioko coastal forests at the southern end of the range, and by Guinean forest-savanna mosaic along the central and northern ends of the range; the Cameroon Highlands form the boundary between the Guinean and Northern Congolian forest-savanna mosaic ecoregions.The highest mountain in the chain, Mount Cameroon is considered a separate ecoregion, while the highest peak within the region is Mount Oku ().