The existing Jamrud fort was built by Hari Singh Nalwa in December 1836 who had named it Fatehgarh. English explorer William Moorcraft who visited Jamrud in 1824 before the construction of the Sikh fort, noted ruins of a building there. He writes:
“The plain terminated at the foot of the Khyber range. It appeared to have been formerly a place of importance, from the number of broken stone walls scattered about, and some large tanks, one of which was sixty yards square.” 
From 1674 to 1678, the Maharaja Jaswant Singh of Marwar served as thanedar of Jamrud for Mughals. The author of Fatuhat-i-Alamgiri writes: “Meanwhile ‘Ruknus Sultanat’ (the pillar of the state) Maharaja Jaswant Singh came from the thana (post) of Jamrud and paid his respects to the emperor (Aurangzeb Alamgir, at Hasan Abdal), who conferred upon the Maharaja a special robe with an elephant worth Rs.20,000/-, sword with studded hilt and seven trays of fruits.” 
1- “Travels in the Himalayan provinces of Hindustan and the Panjab; in Ladakh and Kashmir; in Peshawar, Kabul, Kunduz, and Bokhara”, William Moorcroft, p-345
2- ‘The Culcutta Review’, 1844, p-484
3- ‘Futahat-i-Alamgiri’ by Ishwardas Nagar, English translation, p-111
4- “Peshawar : Historic city of the frontier” by Hasan Dani“, p-195.