The British Empire was the biggest and strongest empire in history covering 33.7 million km2. It had the largest landmass, military, percent of world GDP and population than any other empire throughout history. Many disputes arose throughout the empire which lead to it’s downfall. The Mongolians had the fastest growing and largest continuous empire covered over 24,000,000 km2 within 30 years, but the Mongolian Empire struggled to last 100 years before war split the empire into many factions.
via 3000 years history of different empire(Strongest Mongol Empire) – YouTube.