stylistic:style_transfer, stylistic:tone, information:filtering, linguistic:voice_change, quality:corruption
Urbanisation

The Arab conquest of Persia led to a period of extreme urbanisation in Iran, starting with the ascension of the Abbasid dynasty and ending in the 11th century CE. This was particularly true for the eastern parts of the country, for regions like Khorasan and Transoxiana. During this period, Iran saw the development of massive metropolises, some reaching population numbers of up to 200,000 people. This period of extreme urbanisation was followed in the late 11th and early 12th century by a collapse of the Iranian economy, which led to large scale emigrations of Iranians into Central Asia, India, the rest of the Middle East, and Anatolia. This catastrophe has been cited by some as reason for the Persian language becoming widespread throughout Central Asia and large parts of the Middle East.