I would go with 'Major sandstorms destroyed the crops' because the Indus Valley civilization most likely declined by something affecting the food.
A lot of places hun. All you have to do is look it up online. Most of the people in here will get it wrong. You can look it up.
~Ava~
Yalta Conference and deciding the future of Germany and Poland
Germany invaded Poland unprompted, which started WWII.
Answer:
I got 670 but I'm not 100% sure so if im not correct I apologize