From 6500 to 4000 BCE, the Sumer civilization increased in social polarization. For example, central houses in the settlements became bigger. This early Sumer culture is characterized by large unwalled villages with multi-roomed rectangular mud-brick houses. The village featured public buildings including temples and centralized government. They had fine quality greenish colored pottery decorated with geometric designs in brown or black paint. Their known tools that survived the test of time included sickles made of hard fired clay, stone, and metal and the use of ploughs. Villages included craftspeople, potters, weavers and metalworkers, but the bulk of the population were farm workers.
The known Sumerian city-states written history goes back to before 2700 BCE, and starting about 2300 BCE the records are fairly complete.
