Persian (Persian: فارسی Fārsi [fɒːɾˈsiː]) is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran (Persia) (locally referred to as Farsi or Parsi), Afghanistan (officially known as "Dari Persian" since 1958 for political reasons), Tajikistan (officially known as "Tajik" since the Soviet era), and other countries which historically came under Persian influence. The Persian language is classified as a continuation of Middle Persian, the official religious and literary language of Sassanid Persia, itself a continuation of Old Persian, the language of the Persian Empire in the Achaemenid era. Persian is a pluricentric language and its grammar is similar to that of many contemporary European languages.