As such they rely on international trade for their agricultural produce.
One effect of globalization is that it pushes countries to concentrate on the good or service that they excel in and just import everything else. Through globalization, all the goods of all the countries become open and available for everyone in what is called a global market. As such, if a country finds it hard and expensive to produce a certain good, it would buy it from another country instead.
For example, a country with a cold climate like Alaska cannot produce mangoes as such only grows in tropical countries. If it would still insist on producing mangoes, it would have to build a facility with artificial sunlight and heat. This would be extremely expensive. However with globalization, it would be cheaper for Alaska to import mangoes from Mexico or from Asian countries. Alaska can now concentrate on its petroleum extraction, a thing they do best.
In our first example, Arab countries produce petroleum products but cannot produce adequate agricultural products for their citizens. Since they need to import agriculture products, they need money. As such, instead of producing just an adequate amount of petrol for their domestic consumption, they need to produce more so they can sell it and earn the money they need for the importation.