to release some of the population towards more diversified and specialized activities. Thus, it is clear that agricultural surplus, considered important by Childe (1950) (discussed in Lesson 1), was common in Sumerian cities. It helped to create a stratified society.Since most of the early cities were dependent on agriculture and irrigation, rivers played a major role in urban location. The rivers were also a means of communication which allowed Sumerian cities to have trade relations with other civilizations of the Indian Ocean (particularly, the Indus Valley). The major elements traded were timber, luxury goods, and metal.Arts, Disciplines and ScriptsAccording to Childe (1950), urban societies were characterised by the presence of artists. In Sumerian civilization, artists were involved in stone, metal, and jewellery work as well as seal cutting.With regard to knowledge and science, mathematics, astronomy, astrology and medical surgery were studied. Writing was an important characteristic of this civilization and clay was the common writing material. The earliest writings were of an economic and administrative nature followed by legal documents and finally by epics and myths.Urban PlanningMost buildings in Sumer faced northwest because of the prevailing wind. The palace and dwellings of individuals from the upper social strata followed that alignment. Although ancient cities reflected very little planning, some zoning was found in them.The main area of the house was the central court around which there were secondary rooms. At the initial stages of city development there were open spaces between the houses. As the population increased, new buildings were constructed in those open lands thereby limiting the amount of open space or green areas. Most of the cities were characterised by very narrow lanes and dead end alleys.Within the cities, social and economic status were associated with a few occupations such as priests, temple administrators, and those working for the palace. Socio-economic differences were also reflected in terms of housing structures. High income groups lived in two storey buildings while common individuals lived in one storey structures.