5 000 years – 5 millimetres
The first civilizations are established in Mesopotamia, Egypt and China. Writing is invented. Indicators of civilization are: advanced agriculture, city-dwelling, specialized professions, advanced governance and writing. The motions of the celestial bodies are used for calendars.
Kuva: Egypt was among the earliest civilizations. Christian Jegou
The first high cultures started to form at about 5000 years ago in Mesopotamia, Egypt and China. The skill of writing marked the beginning of the historical time. The knowledge started to accumulate in an unprecedented way as passing of the culture and innovations from generation to generations was not anymore dependent only on oral tradition. Other features of the high cultures include more advanced agriculture, connubial lifestyle, separation of different occupations and development of governmental organizations. Societies became bigger and more hierarchical.
The Sumerians developed picture writing at bout 5200 years ago (at 3200 bc), and the cuneiform writing a few hundred years after this. The beginning of literacy, or the written language starts the historic era. At the same time appear also the signs of the human curiosity for studying the nature. At about 4000 years ago, several different city-states were combined into the kingdom of Babylonia, and this was the founding time for the large star-maps of the sky, our current astrological star signs, and our current habit of dividing the time into 60-divisional units (there is 60 seconds in a minute, 60 minutes in an hour), and using a 7-day week. At the same time, the Egyptians in the Nile delta were developing geometry, and building pyramids. Egyptians also started to use the annual calendar with 365 days.