Agra is located about 139 miles southeast of Delhi along the west bank of the River Jumna. Located between Mathura and Surajpur, and referred to by Greek historians as Methoras and Cleisobora, Agra was part of the Surasena Empire, with Mathura as the capital. Geographically, Agra is centrally located in northern India, imbuing it with political and commercial strategic advantage. Many battles have been fought for control of the city, and it became the capital city during the sixteenth and seventeenth centuries. The fortified core composed by the Agra Fort originally served the Rajputs, as an impregnable, protective, screen against invasions. It finally fell in 1081 to Mahmud Shah, the governor of the northwest regions and the Punjab. Jaipal, then the Rajput ruler, defended the fort valiantly but surrendered to the Ghaznavid army when reinforcements failed to arrive. Though Agra was sacked and owed its allegiance to Ghazni, the Rajput rulers still effectively controlled it. It was during the Second Battle of Tarain (1192) that the Ghaznavids led by Muhammad bin Sam established their rule.