Though, African ancestry is common throughout the Dominican Republic, today it is more prevalent in eastern areas such as San Pedro de Macorís, La Romana, and the Samaná Peninsula, as well as along the Haitian border, particularly the southern parts of the border region; it is least prevalent in the Cibao Valley (especially within the Central Sierra region), and to a lesser extent, in some rural communities in El Seibo and La Altagracia provinces, and the western half of the National District as well. However, in the 19th and early 20th century, African ancestry was higher in the southwestern region than in the eastern region, due to the impact of the Afro-Antillean and Haitian immigration during the 20th century.