Hindustani vocabulary, also known as Hindi-Urdu vocabulary, like all Indo-Aryan languages, has a core base of Sanskrit, which it gained through Prakrit. As such the standardized registers of the Hindustani language (Hindi-Urdu) share a common vocabulary, especially on the colloquial level. However, in formal speech, Hindi tends to draw on Sanskrit, while Urdu turns to Persian and sometimes Arabic. This difference lies in the history of Hindustani, in which the Khariboli dialect started to gain more Persian words in urban areas (such as Lucknow and Hyderabad), under the Delhi Sultanate; this dialect came to be termed Urdu. The original Hindi dialects continued to develop alongside Urdu and according to Professor Afroz Taj, "the distinction between Hindi and Urdu was chiefly a question of st