If we look even farther back, to the previous interglacial period, which peaked around 125,000 years ago, we do find evidence of warmer temperatures. The evidence suggests the long-term average temperature was probably no more than 1.5˚C (2.7˚F) above preindustrial levels—not much more than the current global warming level.
Without rapid and sustained reductions in greenhouse gas emissions, the Earth is currently on course to reach temperatures of roughly 3˚C (5.4˚F) above preindustrial levels by the end of the century, and possibly quite a bit higher.
At that point, we would need to look back millions of years to find a climate state with temperatures as hot. That would take us back to the previous geologic epoch, the Pliocene, when the Earth’s climate was a distant relative of the one that sustained the rise of agriculture and civilization.