Southern Uzbek, also known as Afghan Uzbek, is the southern variant of the Uzbek language and an official language of Afghanistan where it is based and has up to 4.2 million speakers. It uses the Perso-Arabic writing system in contrast to the language variant of Uzbekistan. Southern Uzbek is intelligible with the Northern Uzbek spoken in Uzbekistan to a certain degree. However it has differences in grammar and also many more loan words from Afghan Persian (in which many Southern Uzbek speakers are proficient).