There used to be nearly complete equality of poverty throughout the world. But the Industrial Revolution in the 1750s, which began in England, ushered in a period modern economic growth. Societies moved from economies based on agriculture, to economies based on technologies.
Countries grew, and can grow, through two mechanisms. It is important to understand the differences between the two mechanisms, because different institutions are needed to enable them.
Endogenous growth is based on continuing innovation that increase productivity. And throughout history, there have been waves of technological breakthroughs.
Countries who are not at the technological forefront can catch up by taking on technologies used by advanced countries. But, whether these advances diffuse to other places are affected factors such as proximity to markets, agricultural potential, energy resources, a healthy environment, and politics.
World War I halted economic growth. And after World War II, the world could be said to be divided into three parts. In the first world (USA, Europe, Japan) recovered quickly from World War II and endogenous growth took hold. Countries who adopted communist systems (Soviet Union, People’s Republic of China) initially experienced industrialisation, but economic development subsequently slowed, and the countries eventually opened up. The so-called third world (and sometimes, fourth world), comprising former colonial powers who went through decolonisation, had a mix of economic histories and strategies. Many countries caught up or are catching up, while others remain under-developed.