The ruins of Mohenjo-daro, located in the southern province of Sindh near the Indus River, and a UNESCO World Heritage Site, are considered among the best-preserved urban settlements in South Asia. They were discovered in 1922, and mystery still surrounds the disappearance of its culture, which coincided with those of ancient Egypt and Mesopotamia. The recent floods did not directly affect Mohenjo-daro, but record-breaking rainfall damaged the ruins, said Ahsan Abbasi, the site’s curator. “Many great walls built nearly 5,000 years ago have collapsed due to monsoon rains,” Abbasi said. He said dozens of builders under the supervision of archaeologists had begun repair work. Abbasi did not give an estimated cost of the damage. The site’s landmark “Buddhist Stupa,” a large hemispherical structure associated with worship, meditation and burial, remains intact, Abbasi said. But the rains have damaged some outer walls and also some larger walls that separate individual rooms or wards. Abbasi said the civilization at Mohenjo-daro, also known as the “Mound of the Dead” in the local Sindhi language, built an elaborate drainage system, which was crucial for floods in the past. Although the floods have touched the whole of Pakistan, the province of Sindh has been hit the hardest. On Monday, army engineers made a second cut in an embankment in Lake Manchar, Pakistan’s largest freshwater lake, to release rising waters in hopes of saving the nearby town of Sehwan from heavy flooding. Water from the lake has already flooded dozens of nearby villages, forcing hundreds of families to hastily leave their homes. Rescue operations continued on Tuesday with troops and volunteers using helicopters and boats to evacuate people from flooded areas and the nearest relief camps. Tens of thousands of people already live in such camps, and thousands more have taken refuge on roadsides on higher ground. Ghulam Shabir, 52, from the outskirts of Szechuan, said he had fled his home three days ago after authorities told them to evacuate. “I took my family members with me and came to this… safer place,” he said. He echoed the complaints of many other villagers that no government aid had yet reached them. Shabir said he did not know whether his house had collapsed or not. The prime minister, Shehbaz Sharif, urged Pakistanis in televised remarks on Tuesday to donate generously to flood victims, most of whom rely on government aid to survive. Sharif has repeatedly called on the international community to send more aid to the flood victims. He said that Pakistan is facing a tragedy caused by climate change. The UN refugee agency said it had handed over thousands of tents and other emergency supplies to the Sindh government. Last week, UN Secretary-General Antonio Guterres called on the world to stop “sleepwalking” through the crisis. He plans to visit flood-affected areas on September 9. According to Pakistani officials, Guterres will travel to Sindh, but it is unclear whether he will visit the archaeological site.