On average, income inequality within developing economies is very high, particularly in Africa, and higher than in the industrialized world, which creates its own major development challenges. But, in aggregate, global income inequality has declined from the late 1980s, and particularly rapidly from about 2008, as developing economies have, on average, closed some of the gap with industrialized countries. Previously, at least since the early 19th century, global inequality had increased. The driving factors behind this change have included the very real impact of globalization and technology on trade and employment, and also the transition of the formerly Communist bloc in Eastern Europe.
Nolan, B., Rebhari, E., Richiardi, M., Valenzuela, L. & Nabarro, B. (2017). 'Inequality and Prosperity in the Industrialized World: Addressing a Growing Challenge'. Citi GPS: Global Perspectives & Solutions, October.