The Azerbaijan Democratic Republic, the first democratic and secular republic in the Muslim world, was established in 1918, but was incorporated into the Soviet Union in 1920. Azerbaijan regained independence in 1991. The Constitution of Azerbaijan does not declare an official religion but the majority of people adhere to the Shia branch of Islam, although Muslim identity tends to be based more on culture and ethnicity rather than religion and Azerbaijan remains as one of the most liberal majority-Muslim nations. The pre-Turkic Azerbaijani population spoke an Iranian language called the Old Azeri language, which was gradually replaced by a Turkic language, now known as the Azerbaijani language from the 11th century onward until it became completely extinct in the 16th century. To distinguish it from the Turkic Azerbaijani or Azeri language, this Iranian language, is designated as the Azeri language (or Old Azeri language), because the Turkic language and people are also designated as "Azeri" in the Persian language.
Azerbaijan is in the South