It is a sad truth that most of us don't know much about the world beyond our world. One of the ways we learn about new countries is when they go to war. I learnt about Kuwait that way when I was 10 years old during the first Gulf War. Kuwait is about the same size as Swaziland, but has a population about the same as Croatia (4.3 million v Swaziland's 1.1 million). Kuwait is the 5th richest country by GDP per person (adjusted for how expensive things are) while Swaziland is 109th. The big difference is Oil - the black liquid gold some people were randomly born above. Kuwait had already done well as a centre for boat building in the Persian region, using a relationship with Britain to stay separate from the Ottoman Empire. But the Oil Boom led the Golden Era of 1946-1982, and Kuwait started the world's first Sovereign Wealth Fund in 1953 (The Kuwait Investment Authority) diversifying away from reliance on Black Gold.
Richest Countries by GDP per Capita