Sikhism achieved a series of military victories and created a Sikh Empire in 1799. The Sikh empire had its capital in Lahore, spread over almost comprising what is now northwestern Indian subcontinent. The Sikh Empire entered into a treaty with the colonial British powers, with each side recognizing Sutlej River as the line of control and agreeing not to invade the other side. Ranjit Singh's most lasting legacy was the restoration and expansion of the Harmandir Sahib, most revered Gurudwara of the Sikhs, with marble and gold, from which the popular name of the "Golden Temple" is derived. After the death
Sikh scriptures They have been referred to as the "Key to the Sri Guru Granth Sahib" by Guru Arjan Dev, the fifth Sikh guru. He was the first scribe of Guru Granth Sahib and a scholar of great repute. From his work, it is clear that he had mastery of various Indian languages and had studied many ancient Indian religious scriptures. Panjab Digital Library in collaboration with the Nanakshahi Trust took up digitization of Sikh scriptures in 2003. Thousands of manuscripts have been digitized and are available online at Panjab Digital Library. Sikh scriptures The principal Sikh scripture is the "Adi Granth"