The richest families in Florence, Italy have had it good for a while—600 years to be precise.

That's according to a recent study by two Italian economists, Guglielmo Barone and Sauro Mocetti, who after analyzing compared Florentine taxpayers way back in 1427 to those in 2011. Comparing the family wealth to those with the same surname today, they suggest the richest families in Florence 600 years ago remain the same now.

"The top earners among the current taxpayers were found to have already been at the top of the socioeconomic ladder six centuries ago," Barone and Mocetti note on VoxEU. The study was able to exploit a unique data set—taxpayers data in 1427 was digitized and made available online—to show long-term trends of economic mobility.

While researchers admit the flaws to tracing family wealth using surnames, they point out Italian surnames are usually highly regional and tend to pass on linearly. The families at the top of the socioeconomic ladder six centuries ago are the top earners among current taxpayers. Those at the top of the ladder had the most prestigious jobs, while families at the bottom had less esteemed occupations, with earnings below the median.

While it comes as little surprise that families pass on their wealth to their children, it's still somewhat remarkable that these families were able to maintain their wealth through various sieges of Florence, Napoleon's campaign in Italy, Benito Mussolini's dictatorship, and two world wars.

The study adds further evidence on how the rich remain rich. In England, researchers have previously demonstrated how a family's status in England can persist for more than eight centuries, or more than 28 whole generations. It's a trait shared by elite families in China, whose high status has persisted since the Mao years.