Reeta Grewal's study of Urban Patterns in Punjab discusses the region's population centers throughout the 19th and 20th century. Link to the study can be found here

http://www.global.ucsb.edu/punjab/sites/secure.lsit.ucsb.edu.gisp.d7_sp/files/sitefiles/journals/volume20/12-Reeta%20Sharma%2020.pdf

As a context to the map, the top left most with 100k and more population is Peshawar.

The large population in the center next to Ravi is Lahore, and Amritsar to its right. Cities to the east of Beas are Jullundur and Ludhiana. Center-left top is represented by Rawalpindi and Sialkot to the south-east of Chenab. On either side of Sutluj are Ferozepur and Kasur.