What was the greatest achievement of the indus valley civilization?

(1) They were among the first to develop a system of uniform weights and measures. Their building bricks were very uniform making city planning easy. 

(2) This was the first civilization to incorporate urban sanitation systems. Personal hygiene seems to have been a high priority. 

(3) Their art was highly advanced. Terracotta, steatite and bronze human and animal figurines with anatomically correct proportions have been found. Their jewelry was complex and considered beautiful by today's standards. Long carnelian beads were a specialty. 

(4) Transportation and trade were major goals of these people. Their trade network ran from Mesopotamia to northern and central India. Their empire was economic, not military. 

(5) Indus Valley Civilization agriculture was based upon a highly productive method of raising, storing and transporting domesticated wheat and barley. Other crops were known. 

(6) They had a written script, mostly used on inscribed seals. The language and scripts are still being investigated and are controversial. 

(7) Formal religion was highly advanced and included burial and cremation of human remains. 

Keep in mind that the civilizations may have had no standing army, just a police-type force.