Why countries in the Middle East large exporters of agricultural products such as wheat and corn?

This is not accurate. Middle Eastern countries are generally not considered to be large exporters of agricultural products such as wheat and corn. Many countries in the Middle East have arid climates and limited water resources, making it difficult to produce sufficient agricultural products for domestic consumption, let alone for export. Instead, several Middle Eastern countries are net importers of agricultural products, relying on imports from countries with more favorable agricultural conditions to meet their domestic needs.