Why is the Huang He ( Yellow) Roger valley known as the “ cradle of civilations in China”

What do sellers do if they expect the price of goods they have for sale to increase dramatically in the near future? store the goods indefinitely regardless of when the price rises store the goods until the price rises and then try to sell them sell the goods now and try to invest the money instead of resupplying sell the goods now but try to get the higher price for them