Member states of the Organisation of Islamic Cooperation

The Organisation of Islamic Cooperation founded in 1969 has 57 members, 56 of which are also member states of the United Nations with 42 countries being Muslim majority countries. Some, especially in West Africa, are – though with large Muslim populations – not necessarily Muslim majority countries. A few countries with significant Muslim populations, such as Russia and Thailand, sit as Observer States, while others, such as India and Ethiopia, are not members because they have a low population of Muslims.
The collective population of OIC member states is over 1.8+ billion as of 2011.
The green country’s (see above) they have majority Muslim population like Saudi Arabia or Sudan.