Dari (, , ), also known as Dari Persian (, ), is the variety of the Persian language spoken in Afghanistan. Dari is the term officially recognised and promoted since 1964 by the Afghan government for the Persian language, hence it is known as Afghan Persian or Eastern Persian in many Western sources. As Professor Nile Green remarks "the impulses behind renaming of Afghan Persian as Dari were more nationalistic than linguistic" in order to create an Afghan state narrative. Apart from a few basics of vocabulary, there is little difference between formal written Persian of Afghanistan and Iran. The term "Dari" is officially used for the characteristic spoken Persian of Afghanistan, but is best restricted to formal spoken registers. Persian-speakers in Afghanistan still prefer to call their language “Farsi,” while Pashto-speakers may sometimes refer to it as "Parsi." Farsi Dari serves as the lingua franca for interethnic communications in Afghanistan. As defined in the Constitution of Afghanistan, it is one of the two official languages of Afghanistan; the other is Pashto. Dari is the most widely spoken language in Afghanistan and the native language of approximately 40–45% of the population. Dari serves as the lingua franca of the country and is understood by up to 78% of the population. Dari served as the preferred literary and administrative language among non-native speakers, such as the Pashtuns and Mughals, for centuries before the rise of modern nationalism. Also, like Iranian Persian and Tajiki Persian, Dari Persian is a continuation of Middle Persian, the official religious and literary language of the Sassanian Empire (224–651 AD), itself a continuation of Old Persian, the language of the Achaemenids (550–330 BC). In historical usage, Dari refers to the Middle Persian court language of the Sassanids. Etymology Dari is a name given to the New Persian language since the 10th century, widely used in Arabic (compare Al-Estakhri, Al-Muqaddasi and Ibn Hawqal) and Persian texts. Since 1964, it has been the official name in Afghanistan for the Persian spoken there. In Afghanistan, Dari refers to a modern dialect form of Persian that is the standard language used in administration, government, radio, television, and print media. Because of a preponderance of Dari native speakers, who normally refer to the language as Farsi (, "Persian"), it is also known as "Afghan Persian" in some Western sources. There are different opinions about the origin of the word Dari. The majority