Urdu basically is a Khadi Boli Idiom which developed in the North India especially in and around Delhi by the end of the twelfth century A.D. This was the time when due to the settlement of Muslims comprising Turks, Afghans and Iranians; and establishment of the Muslim rule in Delhi, certain socio-political, cultural and linguistic changes were taking place in North India. It was during this period that Khadi Boli came under the influence of new linguistic and cultural forces and eventually became a full-fledged language called ‘Urdu’. Though the structure of Urdu is purely Indo-Aryan, its vocabulary is largely derived from Persian and Arabic and it is written in an ‘adaptation’ of the Perso-Arabic script. (Beg, 1986).The same Khadi Boli style of Urdu is termed by P. B. Pandit (1977, p. 57) as ‘the Northern lingua franca’. In course of its development, the Khadi Boli style of Urdu was known by various names such as Rekhta, Zaban-i-Delhi, Zaban-i-Dehlavi, Zaban-i-Hindostan, Hindostani,... Это и многое другое вы найдете в книге Phonological Variations: A Case Study of Urdu in India (Somana Fatima)