After the independence of Pakistan in 1947, the minority Hindus and Sikhs migrated to India while many Muslims refugees from India settled down in the Dera Ghazi Khan District (map). Many Hindus and Sikhs from Dera Ghazi Khan settled in Delhi found Derawal Nagar along with the migrants from Dera Ismail Khan.

Link: https://www.triposo.com/loc/Dera_Ghazi_Khan/history/background

Link: https://en.wikipedia.org/wiki/Derawal_Nagar