According to Guinness World Records, which seems a good authority, the solution is the Achaemenid Empire in 480 B.C. Also referred to as the Persia, it’s estimated that 44% of the world’s population was ruled from the Achaemenid throne in what’s 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 worldwide population is merely a method to live the expanse of an empire and a few questions whether it’s really fair to use that metric when comparing empires from different time periods. For instance, when the Achaemenid Empire was at its height, there had been only 112.4 million people alive. British ruled-over a relatively meager quarter of the world’s population in 1901, but by then the worldwide population had swelled to 1.6 billion people. Is it reasonable to compare British & Achaemenid empires with this metric? Or are we comparing apples & oranges?
That’s without stepping into the pros and cons of the opposite ways to live size: largest land mass; largest contiguous land mass; largest army; largest gross-domestic-product; and so on.
Instead, we use a metric to find out the long-term influence & stability, said Martin Bommas, an Egyptologist & director of the Macquarie University History Museum in Sydney, Australia because it’s one thing to start warring campaigns to amass land but it takes a special set of logistical skills & infrastructure to stay & administer those territories.
“For me, the metric would be counted in years” Bommas said. “Look at Hitler’s Third Reich; it took tons of territory to rival the Romans but nobody would call it an empire because it only lasted 6 years & during a period of total war.”
“I think that to be classed as an empire, you would like to possess a period of peace to bring prosperity” Bommas added. That prosperity can then be exploited in order that resources & wealth are often sent back to the motherland, Bommas said.
That’s where the Genghis Khan’s Mongol Empire fails as a contender for the world’s largest empire. While it can legitimately claim to be the greatest contiguous land empire, it didn’t last that long. Just 88 years after its founding, the empir’e was divided into four separate khanates because Genghis Khan’s descendants squabbled over the road of succession and most of the Mongol Empire’s relatively brief unity was spent engaged in battle with outsiders, aggressively expanding its borders at what proved to be an unsustainable-rate.
The British Empire might not be contiguous but it beats the Mongols in terms of land mass under its control. “It was so massive that we almost struggle to grasp it today” said Bommas. “The sun literally didn’t set on British Empire and it wasn’t just land that was controlled; the seas were dominated by British.”
The British Empire emerged in the late 1500s, when the then separate kingdoms of England & Scotland established their first overseas colonies in Americas & Caribbean. On a technical level, you’ll make an argument that British Empire still exists, albeit during a dramatically diminished sense, through its continued possession of 14 relatively minor overseas territories including Gibraltar & Falkland Islands. There also are 16 independent countries, also referred to as Commonwealth Realms where Queen Elizabeth II remains the top of state including Australia, Belize, Canada, New Zealand, Papua New Guinea & a number of other Caribbean countries. But most agree it ended in 1997 when the UK handed Hong Kong back to China, Bommas said.
“Prince Charles said that Hong Kong marked the end” Bommas said. “It was the last major colony in the empire so I’m happy to go with him that one.”
If we agree with Charles, then British Empire lasted roughly 400 years which suggests that though British conquered more parts of the world than anyone else, they still cannot be called the most important empire when measured by longevity. The Ottoman Empire, governed from modern-day Turkey, outlasted British Empire because it ruled for a minimum of 600 years. But it had been the Romans, assuming you agree that the Roman Empire persisted when it split in two to make the Western Roman Empire & the Eastern Roman Empire, the latter of which lasted the longest at on the brink of 1500 years.
“If you look at it through years lasted, the Romans won this competition hands down” Bommas said.