Continuing through the Reinhart-Rogoff paper I mentioned yesterday, I came across this amazing figure which shows the average inflation rate across all the countries in their sample back to 1500! It's great to have datasets that cross over back into the pre-industrial era.
Prior to the early 1800s, the world was largely pre-industrial (the Watt steam engine was invented in 1775, the first practical steamboat came in 1802, and the Stockton and Darlington railway opened in 1825). Pre-industrial societies produced a very small economic/energy surplus, and grew very slowly. During this era, inflation was on average a few percent, with broad fluctuations.
Once fossil fuel powered industry became widespread, economies could and did grow a lot faster. It appears to have been a little difficult to grow the money supply fast enough under the circumstance - inflation is noticeably lower in the nineteenth century: under 2% almost all the time, with several decade-long deflations in the mix.
Then in the twentieth century, we see the widespread use of fiat currency, which can (as long as you don't let all the banks collapse as in the great depression) generally maintain some minimum inflation rate. The drawback, also clear in the data, is that it allows stressed-out or profligate government to inflate much faster than pre-industrial governments ever could (back in the day that one had to physically melt the old currency down and re-issue the debased version).