History of the world
Whether in prehistoric or historic times, people always needed to be near reliable sources of potable water. Settlements developed on river banks as early as 3000 BCE in Mesopotamia, on the banks of Egypt's Nile River, in the Indus River valley, and along China's rivers. As farming developed, grain agriculture became more sophisticated and prompted a division of labour to store food between growing seasons. Labour divisions led to the rise of a leisured upper class and the development of cities, which provided the foundation for civilization. The growing complexity of human societies necessitated systems of accounting and writing.
Writing
The earliest known hieroglyphic date back to the second half of the 4th millennium BC, such as the clay labels of a Predynastic ruler called "Scorpion I" (Naqada IIIA period, c. 32nd century BC) recovered at Abydos (modern Umm el-Qa'ab) in 1998 or the Narmer Palette, dating to c. 3100 BC, and several recent discoveries that may be slightly older, though these glyphs were based on a much older artistic rather than written tradition. The hieroglyphic script was logographic with phonetic adjuncts that included an effective alphabet. The world's oldest deciphered sentence was found on a seal impression found in the tomb of Seth-Peribsen at Umm el-Qa'ab, which dates from the Second Dynasty (28th or 27th century BC). There are around 800 hieroglyphs dating back to the Old Kingdom, Middle Kingdom and New Kingdom Eras. By the Greco-Roman period, there are more than 5,000.