Middle East countries
Refers collectively to the nations of the Middle East region. Often used in geopolitical or economic contexts.
The Middle East countries are major oil-producing nations.
Trade with Middle East countries is increasing.
中東 means 'the Middle East' as a region, while 中東諸国 explicitly refers to the countries within that region.
Compound of 中東 (Middle East) and 諸国 (various countries).