El nino poses threat to agricultural production in Southern Africa.

Iam pretty sure it is c. 2000 bce

Summer months are the wettest.

Where is the map from the question?

If a particular resource is not useful or needed then the price would be considerably low. once that resource is needed the price or value will raise depending on how useful or needed it is especially if the resource is low in quantity, the consumers would pay whatever they have to, to get that material.