Banyumasan, colloquially known as Basa Ngapak, is a dialect of Javanese spoken mainly in three areas of Java: the Banyumasan region, located in westernmost Central Java Province and surrounding the Slamet mountain and Serayu River; a neighboring area inside West Java Province; and northern region of Banten Province. This area includes Majenang, Cilacap, Gombong, Kebumen, Banjarnegara, Purbalingga, Purwokerto, Bumiayu, Slawi, Pemalang, Tegal, and Brebes regencies.