This civilization, knowing the writing, having some urban centers and a social and economic structure, was rediscovered in 1920 during excavations at Mohenjo-Daro in Sindh near Sukkur and Harappa, in western Punjab and southern Lahore. Many sites, extending from North of the base of Himalaya to the East of Indian Punjab, until the Gujarat in South and East and until the Baluchistan in the West, have also been discovered and studied. Although the archaeological site of Harappa was partially damaged, in 1857, by the engineers building the Lahore-Multan railroad, who used bricks from the ruins of Harappa as ballast.