According to Guinness World Records, which seems as good an authority as any, the answer is the Achaemenid Empire in 480 B.C. Also known as the Persian Empire, it’s estimated that 44% of the world’s population was ruled from the Achaemenid throne in what is now modern-day Iran, making it history’s largest empire by this measure.
However, perhaps unsurprisingly, not everyone agrees. That’s because the share of the global population is only one way to measure the expanse of an empire, and some question whether it’s really fair to use that metric when comparing empires from different time periods. For example, when the Achaemenid Empire was at its height, there were only 112.4 million people alive. The British ruled over a comparatively