75% of Urdu vocabulary comes from Sanskrit & Prakrit. In the late 19th century, a famous Urdu linguist named Syed Ahmad Dehlavi compiled Farhang-e-Asafiya, which is considered till date to be the most reliable Urdu Dictionary. In his dictionary of 55,000 Urdu words, around 75% of the words were actually from Sanskrit and Prakrit.
Urdu was born in the Haryana-UP region. It is a few foreign Perso-Arabic words squatting on Hindi. The word Urdu as a language first appears in the couplet of poet Mashafi (c.1800). Before this, Urdu itself as a distinct language from Hindi did not exist. What existed was Hindi or Hindavi.