The Punjab Frontier Force was established on 18th May 1849 as the Transfrontier Brigade. It became the Punjab Irregular Force in 1851 and finally the Punjab Frontier Force in 1865. There were originally six Punjab Infantry regiments and five of cavalry as well as artillery.
The four Sikh regiments sprung from the disbanded regiments of Sikhs following Gough's victory at Sobraon (10th Feb 1846) at the end of the First Sikh War. Together with some artillery they formed the Frontier Brigade. This name was dropped the following year and they became the 1st, 2nd, 3rd and 4th Regiments of Sikh Local Infantry. In 1851 these four and the famous Corps of Guides were added to the Punjab Irregular Force. The P I F as it was known, became famous throughout the Empire and the men who served in it were proud to call themselves 'Piffers' long after the name changed.
Despite its title, the 51st Sikhs was compoed of Punjabi Musalmans, Dogras and Pathans as well as Sikhs. As the 1st Sikhs they saw much action in the 2nd Afghan War and helped quell the Boxer Rebellion in China in 1900. In WW1 they served in India, Aden, Egypt, and Mesoptamia. For their services in the Middle East, they were given the title 51st The Prince of Wales's Own Sikhs (Frontier Force) but in 1922 they became the 1st battalion 12th Frontier Force Regiment. A territorial battalion was raised in March 1922 attached to the 1st but soon became the 11th battalion recruiting only Pathans. In WW2 the 1st served in India, Iraq, Syria and Italy. After the war they were nominated for parachute training to join 2nd Indian Airborne Division. On Partition, the regiment logically went to Pakistan; the Sikhs and Dogras were routed to India.