To the north and south, the forests transition to drier forest-savanna mosaic, a mosaic of drier forests, savannas, and grasslands. To the west, the Congolese forests transition to the coastal Lower Guinean forests, which extend from western Gabon and Cameroon into southern Nigeria and Benin; these forests zones share many similarities, and are sometimes known as the Lower Guinean-Congolese forests. To the east, the lowland Congolese forests transition to the highland Albertine Rift montane forests, which cover the Mountains lining the Albertine Rift, a branch of the East African Rift system. The Congolese Forests are a global 200 ecoregion.