Maharaja Ranjit Singh Ji took Kashmir in 1819.
After the First Anglo-Sikh War the British sold it to Gulab Singh under the Treaty of Amritsar in 1846, for seventy-five lakh rupees. That transaction created the state of Jammu and Kashmir.
The Jalandhar Doab was annexed at the same time.
The Punjab connection is the shawl. Kashmiri weavers moved into Punjab's towns in numbers through the nineteenth century, and the wool industries of Amritsar, Ludhiana and Nurpur were built by them. Amritsar became the finishing and trading centre for Kashmir shawls sold in Europe, and the collapse of that market after the Franco-Prussian War of 1870 ruined weavers on both sides of the Pir Panjal.
The Sikh administration of the valley, from 1819 to 1846, is remembered in Kashmir as harsh: heavy taxation of the shawl trade, the closure of the Jama Masjid at Srinagar for a period, and severe handling of the famine of the 1830s. The Punjab histories tend to record the conquest and not the government.
What is not written down anywhere is the Kashmiri Muslim population of Punjab's cities: when the families came, which trades they entered, and where their descendants are now. Amritsar, Ludhiana and Ferozepur all have quarters that were Kashmiri and nobody has traced them.