Cotton
oil
cattle
clothing and carpets
Cattle
Oil is Venezuela's most valuable export. The country has one of the largest oil reserves in the world and oil exports make up a significant portion of its government revenue.
Cotton represented a majority of American export to china and the rest of the world. For such a valuable resource many people were caught in a crossfire of financial greed. Just as silk proved the most valuable to china, cotton proved the most valuable to America.
One is Iron
Cotton
Spain's most valuable cash crop is citrus fruit, predominately oranges.
if a country has a natural resource that is valuable to private enterprise they usually export it, whatever it is.
The main export in the Middle ages was drugs and gun powder. They also imported toys and plastic.