Because the government were not good.
Using irrigation system was the practice closely associated with most ancient river valley civilization.
Answer:
The Indo-Gangetic Plain, also known as the Indus-Ganga Plain and the North Indian River Plain, is a 630-million-acre (2.5-million km2) fertile plain encompassing northern regions of the Indian subcontinent, including most of northern and eastern India
Explanation:
I think your answer would be C
