Punjab is one of the few regions in this atlas whose modern geography was created by a religious classification, and the classification cut through it.
The 1947 partition of British India drew a boundary through the province on the basis of district religious majorities, with Muslim-majority districts going to Pakistan and Hindu and Sikh majority districts to India. The line was published after independence had already taken effect. What followed was one of the largest and fastest forced migrations of the twentieth century: millions crossed in both directions and hundreds of thousands were killed, with massacres, abductions and the destruction of shrines on both sides. Sikhs and Hindus left the west almost entirely, Muslims left the east almost entirely, and a religiously mixed countryside became two religiously homogeneous ones inside a year.
Sites did not move with their communities. Nankana Sahib, where Nanak was born, and Kartarpur, where he died, are in Pakistan, while the Sikh population that venerates them is overwhelmingly in India, so pilgrimage across the border has been a diplomatic question ever since; a visa-free corridor to Kartarpur was opened in 2019.
Indian Punjab then went through a second violent period. The army operation at the Golden Temple complex in 1984, the assassination of the prime minister that followed, and the organised killing of Sikhs in Delhi and elsewhere are documented in official inquiries, and remain a live grievance rather than a closed chapter.