Family of more than 20 Altaic languages spoken by some 135 million people from the Balkans to central Siberia. The traditional division of Turkic is into four groups. The southeastern or Uighur group comprises Uighur, spoken mainly in Xinjiang, China; and Uzbek, spoken mainly in Uzbekistan, other Central Asian republics, and northern Afghanistan. The southwestern, or Oguz, group includes Turkish; Azerbaijani (Azeri), spoken in Azerbaijan and northwestern Iran; Crimean Tatar, spoken mostly in Ukraine and Uzbekistan; and Turkmen, used in Turkmenistan, northern Iran, and northern Afghanistan. The northwestern, or Kipchak, group includes Kazakh, spoken in Kazakhstan, other Central Asian republics, and western China and Mongolia; Kyrgyz, spoken in Kyrgyzstan, other Central Asian republics, and western China; Tatar; Baskhir, spoken in Bashkortostan and adjacent areas in Russia; Karachay-Balkar and Kumyk, spoken in the Russian Caucasus; and Karaim, with a few speakers in Lithuania and parts of southwestern Ukraine. The northeastern, or Altai, group comprises languages and dialects spoken in Siberia northeast of the Irtysh River and in adjacent parts of Mongolia, including Altai, Khakas, Shor, and Tuvan; and Sakha, spoken in Sakha (Yakutia) republic of Russia and adjacent areas. Distinct from all the other languages is Chuvash, spoken in Russia's Chuvash republic and adjacent areas. The earliest attestations of Turkic are a group of 8th-century funerary inscriptions of northern Mongolia, in a distinctive writing system called runic script, or Turkic runes. With the Islamization of nearly all Turkic peoples southwest of the Irtysh beginning c. 900, Turkic languages began to adopt the Arabic alphabet. Today the Latin alphabet and Cyrillic alphabet are more extensively used.