Income inequality can be measured at different levels of aggregation such as global, continental, international and national levels. Here we consider income inequality at regions defined as equivalent of continental and sub-continental levels. We investigate the economic disparity between regions of the world and among countries within each continent or subcontinent. The empirical results for data availability reasons are mainly based on the second half of the 20th century. The review covers a whole range of measures and methods frequently employed in empirical analysis of the global and regional income inequality and income distribution. Different determinant factors along with quantification of their impacts are presented and empirical results from different case studies are discussed. Finally, these results are contrasted to those obtained based on the WIID covering the same period and group of countries.