Why hasn’t the Ganges Valley been developed by farmers?

In the East of North India lies the valley of the Ganges River, into which a myriad of deep tributaries flow. Significant areas near the mouth were swampy and covered with deep jungle. For a long time, people could not get used to it, since there were no necessary technologies and tools. In the lower reaches of the Ganges, the climate is very humid, and to the west of the delta there is almost no rainfall, and the land needs irrigation with the help of irrigation systems. Without artificial irrigation, only rice, jute or sugarcane can be grown here.