regarding the common phonetic isoglosses shared by Kurdish, Persian, and Baluchi, Mackenzie concluded that the speakers of these three languages may once have been in closer contact. Subdivisions Kurdish is divided into three or four groups, where dialects from different groups are not mutually intelligible without acquired bilingualism. Northern Kurdish (Kurmanji) is the largest dialect group, spoken by an estimated 15 to 20 million Kurds in Turkey, Syria, northern Iraq, and northwest and northeast Iran. Central Kurdish (Sorani) is spoken by an estimated 6 to 7 million Kurds in much of Iraqi Kurdistan and the Iranian Kurdistan Province. Sorani is a written standard of Central Kurdish developed in the 1920s (named after the historical Soran Emirate) and was later adopted as the standard orthography of Kurdish as an official language of Iraq. Southern Kurdish (Pehlewani) is spoken in the Kermanshah, Ilam and Lorestan provinces of Iran and in the Khanaqin district of eastern Iraq. Laki and Kurdali (Palai) are often included in Southern Kurdish, but they have some distinct features. In historical evolution terms, Kurmanji is less modified than Sorani and Pehlewani in both phonetic and morphological structure. The Sorani group has been influenced by among other things its closer cultural proximity to the other languages spoken by Kurds in the region including the Gorani language in parts of Iranian Kurdistan and Iraqi Kurdistan. Philip G. Kreyenbroek, an expert writing in 1992, says: According to Encyclopaedia of Islam, although Kurdish is not a unified language, its many dialects are interrelated and at the same time distinguishable from other Western Iranian languages. The same source classifies different Kurdish dialects as two main groups, northern and central. The reality is that the average Kurmanji speaker does not find it easy to communicate with the inhabitants of Sulaymaniyah or Halabja. Some linguistic scholars assert that the term "Kurdish" has been applied extrinsically in describing the language the Kurds speak, whereas some ethnic Kurds have used the word term to simply describe their ethnicity and refer to their language as Kurmanji, Sorani, Hewrami, Kermanshahi, Kalhori or whatever other dialect or language they speak. Some historians have noted that it is only recently that the Kurds who speak the Sorani dialect have begun referring to their language as Kurdî, in addition to their identity, which is translated to simply mean Kurdish. Mokriani dialect of Central Kurdish is widely spoken in Mokrian. Piranshahr and Mahabad are