There are alot of factors that make it hard for archeologist and historians to search about the indus valley.the most highlighted factors are the enigmatic nature of Indus valley civilization means there is no clear connection to any continuous literary traditions.they have a much harder time imagining the life of Mohenjo-Daro because there isn't any reliable information about the culture of it. the fact that they cannot read the language(s) of the Indus valley means a lot!
The main reason why historians don't have a lot of information on this is because the people of the Indus river valley wrote in a language that historians today can't figure out what it means.
France wanted colonies in Asia but they couldn't get China and India was under British control. So they decided to focus on Indochina, mainly Vietnam, since it was a country that could be very profitable.
