Economic inequality has been growing over centuries, with rare phases of clear inequality reduction only occurring with catastrophic events

From Wealth and Income Inequality in the Long Run of History by Guido Alfani.  From the Abstract:

This article provides an overview of current knowledge about economic inequality, of both income and wealth, in the very long run of history focusing on Western Europe and North America. While most of the data provided by recent research cover the period from the late Middle Ages until today, some insights are also possible into even earlier epochs. Based on these recent findings, economic inequality seems to have been growing over centuries, with phases of clear and marked inequality reduction being relatively rare and usually associated with catastrophic events, such as the Black Death during the fifteenth century or the World Wars in the twentieth. Traditional explanations of long-term inequality growth are found to be unsatisfying, and a range of other possible causal factors are explored (demographic, social-economic, and institutional). Placing today’s situation in a very long-run perspective not only leads us to question old assumptions about the future of inequality (think of current criticism of Kuznets’s hypotheses) but also changes how we perceive inequality in the modern world.