How did the early Indian Civilizations create a lasting culture?

Most people were poor, and did either farming, fishing or making things. The richest people in an Indus city were probably people who owned a lot of land, or traders who controlled the buying and selling of luxury goods, such as rugs, jewels, minerals and metals. Rich traders loaded their goods on ships sailing off across the sea. They wore fine clothes, and lived in big houses with servants and perhaps slaves. Indus people did not use money. It's likely that wealth was measured by how much land a person had or how many cattle, or how many sacks of grain.