Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan, and 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. Persian has ca. 110 million native speakers, holding official status respectively in Iran, Afghanistan and Tajikistan. Persian has had a considerable, mainly lexical influence on neighboring languages, particularly the Turkic languages in Central Asia, Caucasus, and Anatolia, neighboring Iranian languages, as well as Armenian, and Indo-Aryan languages, especially Urdu. It also exerted some influence on Arabic, while borrowing much vocabulary from it after the Muslim conquest of Persia.