A decade from independence, Delhi was a different city. Wilderness and agricultural fields began to give way to residential suburbs, commercial markets and industrial zones. The population doubled: a spurt that hasn’t been seen since, according to the Census. But the Muslim share of the population plunged from 33 percent to less than 6 percent.
“The city that was once a Mughal city, then a British city, had by the 1950s emphatically become a Punjabi city,” according to historian V.N. Dutta. The adjectives for Delhi also changed: what was once stately, languid and literary became boisterous, hearty and enterprising. And its map was transformed.
Land in western Delhi was allotted to refugees after 1947. These refugee colonies, U-shaped with a park in the middle, became the template for subsequent neighborhoods, partly because they were built by the same urban planners who shaped Delhi through the 50s and 60s. But this was the beginning of Rajinder Nagar, West Patel Nagar, Moti Nagar, Kirti Nagar, Punjabi Bagh, Rajouri Garden: overwhelmingly Punjabi neighborhoods that are today quintessentially Delhi. In South Delhi, Lajpat Nagar was another refugee colony.
Here's another article on how Delhi changed with the influx of migrants from Punjab