Typically, the FIRE community is very much focussed on the USA, with a lot of FI-methodology being created there and with long-term backtesting data mostly available for the Dow Jones or S&P500 indexes.
Credit Suisse has commissioned a yearbook (https://www.credit-suisse.com/media/assets/corporate/docs/about-us/research/publications/credit-suisse-global-investment-returns-yearbook-2023-summary-edition.pdf) where they look at all markets going back as far as 1900 and provide us with real (inflation-adjusted) return figures for individual markets. For Equities, bonds and bills.
Using long-term data, recent bear-markets such as the 2000 internet bubble burst, 2008/9 crisis or Covid hardly show up, putting our own short memories in perspective. And it shows that for the last 123 years, a real annualized return of 5% was possible when investing in world equities. In short, nothing new for FIRE people, but rather a deep-dive into country-specific markets, for those who like to add a little something to their All-World ETF.