Regional Manifestations of Globalization: Empires and Control of the "Known" World

British Empire 36.6 million km² 1921
Mongol Empire 33.2 million km² 1279
Russian Empire 22.8 million km² 1895
Spanish Empire 19 million km² 1790
Arab Empire 13.2 million km² 720
Qing Empire 12 million km² 1899
French Empire 11.2 million km² 1914
Portuguese Empire 10.4 million km² 1820
American Empire 10 million km² 1908
Brazilian Empire 8.1 million km² 1865
Achaemenid Persian Empire 7.5 million km² 490 BCE
Japanese Empire 7.4 million km² 1943
Ming Empire 6.5 million km² 1644
Han Empire 6 million km² 220
Ottoman Empire 5.6 million km² 1299-1922
Roman Empire 5.6 million km² 116
Tang Empire 5.4 million km² 756
Macedonian Empire 5.4 million km² 323 BCE
Maurya Empire 5 million km² 232 BCE
Mexican Empire 4.7 million km² 1867

As a reference point, the habitable portion of the globe (i.e. excluding Antarctica) extends over roughly 52, 677,000 square miles (136,433,400 sq. km.)