An ancient Indian law book called the Manusmriti, developed by Brahmin Hindu priests, shaped Punjabi religious life from 200 BC onward.
[10][16] A number of Punjabis during the colonial period of India became Christians, with all of these religions characterizing the religious diversity now found in the Punjab region.
Nevertheless, the common concept was the belief in cycles of reincarnation, or sansār, and was the oldest recorded religion in the region.
[10] It also developed its own distinct doctrines, including the belief that both intrinsic factors (egocentrism, to be ameliorated through devotion and prayer), and external forces (social and political oppression, to be addressed by community service and armed self-defense as needed, and balancing spiritual and temporal power in the world as opposed to renunciation), produced suffering.
In the western Punjab, Baisakhi, the new year's day of the Hindus, is celebrated as an agricultural festival, by all Muhammadans, by racing bullocks yoked to the well gear, with the beat of tom-toms, and large crowds gather to witness the show, The race is called Baisakhi and is a favourite pastime in the well-irrigated tracts.
Then the processions of Tazias, in Muharram, with the accompaniment of tom-toms, fencing parties and bands playing on flutes and other musical instruments (which is disapproved by the orthodox Muhammadans) and the establishment of Sabils (shelters where water and sharbat are served out) are clearly influenced by similar practices at Hindu festivals, while the illuminations on occasions like the Chiraghan fair of Shalamar (Lahore) are no doubt practices answering to the holiday-making instinct of the converted Hindus.
The sects of reformers based on a revolt from the orthodoxy of Varnashrama Dharma were obviously the outcome of the knowledge that a different religion could produce equally pious and right thinking men.
However, between the censuses of 1941 and 1951, a sudden shift towards religious homogeneity occurred in all districts across Punjab owing to the new international border that cut through the province due to the partition of India in 1947.
This rapid demographic shift was primarily as a consequence of wide scale migration but also caused by large-scale religious cleansing riots which were witnessed across the region at the time.