Answer:
New ways of governing were needed.
The people migrated to other lands.
The amount of trade dropped dramatically.
New schools were created to train scholars.
Harappan Civilization's writing has never been decoded. Harappan Civilization is a part of the Indus Valley Civilization. The languages of the Harappan Civilization belong to the Bronze Age and they are still today a mystery. This language is totally unattested to any source that is readable. This is one mystery that is yet to be solved.
That meant that the South would have been starved of supplies and would have been forced to surrender.
