The diverse peoples of the Sahara are usually categorized along ethno-linguistic lines. In the Maghreb, where Arab and Berber identities are often integrated, these lines can be blurred. Some Berber-speaking North Africans may identify as "Arab" depending on the social and political circumstances, although substantial numbers of Berbers (or Imazighen) have retained a distinct cultural identity which in the 20th century has been expressed as a clear ethnic identification with Berber history and language. Arabic-speaking Northwest Africans, regardless of ethnic background, often identify with Arab history and culture and may share a common vision with other Arabs. This, however, may or may not exclude pride in and identification with Berber and/or other parts of their heritage. Berber political and cultural activists for their part, often referred to as Berberists, may view all Northwest Africans as principally Berber, whether they are primarily Berber- or Arabic-speaking (see also Arabized Berber).