The Indus Valley Civilization (IVC) was a Bronze Age civilization (3300–1300 BCE; mature period 2600–1900 BCE) extending from what today is northwest Pakistan to northwest India and northeast Afghanistan (see map). Along with Ancient Egypt and Mesopotamia, it was one of three early civilizations of the Old World, and the most widespread among them, covering an area of 1.25 million km2. It flourished in the basins of the Indus River, one of the major rivers of Asia, and the now dried up Sarasvati River, which once coursed through northwest India and eastern Pakistan together with its tributaries flowed along a channel, presently identified as that of the Ghaggar-Hakra River on the basis of various scientific studies. At its peak, the Indus Civilization may have had a population of over five million. Inhabitants of the ancient Indus river valley developed new techniques in handicraft (carnelian products, seal carving) and metallurgy (copper, bronze, lead, and tin). The Indus cities are noted for their urban planning, baked brick houses, elaborate drainage systems, water supply systems, and clusters of large non-residential buildings. The Indus Valley Civilization is also known as the Harappan Civilization, after Harappa, the first of its sites to be excavated in the 1920s, in what was then the Punjab province of British India, and is now in Pakistan. The discovery of Harappa, and soon afterwards, Mohenjo-Daro, was the culmination of work beginning in 1861 with the founding of the Archaeological Survey of India in the British Raj. Excavation of Harappan sites has been ongoing since 1920, with important breakthroughs occurring as recently as 1999. There were earlier and later cultures, often called Early Harappan and Late Harappan, in the same area of the Harappan Civilization. The Harappan civilization is sometimes called the Mature Harappan culture to distinguish it from these cultures. By 1999, over 1,056 cities and settlements had been found, of which 96 have been excavated, mainly in the general region of the Indus and the Sarasvati Riverand their tributaries. Among the settlements were the major urban centres of Harappa, Mohenjo-daro (UNESCO World Heritage Site), Dholavira, Ganeriwala in Cholistan and Rakhigarhi. The Harappan language is not directly attested and its affiliation is uncertain since the Indus script is still undeciphered. A relationship with the Dravidian or Elamo-Dravidian language family is favored by a section of scholars, while others suggest an Austroasiatic language related to Munda.