Sumer
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia, modern-day southern Iraq, during the Chalcolithic and Early Bronze ages, and one of the first civilizations in the world along with Ancient Egypt and the Indus Valley. Living along the valleys of the Tigris and Euphrates, Sumerian farmers were able to grow an abundance of grain and other crops, the surplus of which enabled them to settle in one place. Prehistoric proto-writing dates back before 3000 BC. The earliest texts, from c. 3300 BC, come from the cities of Uruk and Jemdet Nasr; early cuneiform script emerged around 3000 BC.
Harappa
The Harappan Civilization has its earliest roots in cultures such as that of Mehrgarh, approximately 6000 BC. The two greatest cities, Mohenjo-daro and Harappa, emerged circa 2600 BC along the Indus River valley in Punjab and Sindh. The civilization, with a possible writing system, urban centers, and diversified social and economic system, was rediscovered in the 1920s also after excavations at Mohenjo-daro in Sindh near Larkana, and Harappa, in west Punjab south of Lahore. A number of other sites stretching from the Himalayan foothills in east Punjab, India in the north, to Gujarat in the south and east, and to Pakistani Balochistan in the west have also been discovered and studied. Although the archaeological site at Harappa was damaged in 1857 when engineers constructing the Lahore-Multan railroad (as part of the Sind and Punjab Railway), used brick from the Harappa ruins for track ballast, an abundance of artifacts have nevertheless been found. The bricks discovered were made of red sand, clay, stones and were baked at very high temperature. As early as 1826 Harappa, located in west Punjab, attracted the attention of a British officer in India, who gets credit for preliminary excavations in Harappa.