In terms of demographic dynamism, the colonial period was noted for massive internal migration within Punjab. This was associated mainly with the opening of canal colonies in the western part of the province. During 1886-1947, as many as nine such colonies were developed in the western and southwestern parts of Punjab. Vast stretches of the barren, uncultivable wasteland (locally known as bars) in Lyallpur, Sorgodha, Shahpur, Montgomery, Multan, Gujranwala, Sheikhupura, Gujarat and Sialkot districts were transformed into highly productive land, raising large surpluses of wheat, gram, cotton, rice and fodder. Six million acres of land, earlier inhabited mainly be nomadic herders, was involved (Talbot and Thandi, 2004, p. 1). The canal colonies were meant to meet the imperial needs of wheat and cotton, to raise mares, mules and studs and camels for the police and army, and to decongest the crowded parts of the province.

Around four-fifths of the colonists originated from the seven densely populated districts of Amritsar, Gurdaspur, Jalandhar, Hoshiarpur, Ludhiana, Ambala and Sialkot, located in the central and eastern parts of the province. Two-thirds of them were Jats – Sikh, Muslim and Hindu. Arains and Sikh- Hindu Sainis, Kambohs and Rajputs were among other important groups involved.

- Gopal Krishan in "Demography of the Punjab 1849-1947", Punjab University, Chandigarh

Link to the study:

http://www.global.ucsb.edu/punjab/sites/secure.lsit.ucsb.edu.gisp.d7_sp/files/sitefiles/journals/volume11/no1/6_krishan.pdf

Also the following article provides more information on the development of the canal colonies.

https://tribune.com.pk/story/411007/the-new-land-in-punjab/