The emergence of the new oil states and their increasing importance in world trade in the 1970s brought a renewed interest in thinking on rentier economies in the aforementioned disciplines of political science and international relations. Examples of rentier states include oil-producing countries in the MENA region including Saudi Arabia, United Arab Emirates, Iraq, Iran, Kuwait, Qatar, Libya and Algeria as well as a few states in Latin America, all of whom are members of OPEC. African states such as Nigeria, Gabon, Angola, Ghana, Uganda and South Sudan are also important oil producers with rentier economies, earning income from trading natural resources.