Delhi's population roughly doubled between 1941 and 1951 with the arrival of Punjabi refugees, and the character of the city changed permanently.
The colonies built for them carry the names: Rajinder Nagar, Patel Nagar, Lajpat Nagar, Punjabi Bagh, Model Town, Kalkaji, Nizamuddin East. Refugee markets became commercial centres.
Delhi's food, its business culture, its speech and a good deal of its politics became Punjabi in that decade. Butter chicken was invented in a Delhi restaurant by refugees from Peshawar.
The Delhi Sikh Gurdwara Management Committee, created by statute in 1971, is separate from the SGPC and runs Delhi's historic gurdwaras, and Delhi Sikh politics is a distinct system from Punjab's.
In November 1984 organised mobs killed Sikhs across the city, concentrated in the resettlement colonies where the poorest Sikh families lived. The widows' colony at Tilak Vihar was built for the survivors and is still there.
The refugee colonies were built on the western and southern edges of the old city and are now the middle of it. Karol Bagh, Rajouri Garden, Punjabi Bagh and the Nagars were all allotment schemes.
The 1984 killings were concentrated in Trilokpuri, Sultanpuri, Mangolpuri and the other resettlement colonies where poor Sikh families lived. The commissions that followed ran for decades and the convictions have been very few.
Delhi's Punjabi population is now two and three generations from Punjab and its Punjabi is a Delhi Punjabi. The connection to the villages of origin, which are in Pakistan, ended in 1947.