The Mongol Empire was the largest contiguous land empire in history.

At its height in the 13th century, the empire founded by Genghis Khan stretched from the Sea of Japan to Eastern Europe, covering an estimated 24 million square kilometers — roughly 16 percent of Earth’s total land area — governed as one connected territory rather than as scattered colonies.

The Mongols achieved this in only a few decades through fast cavalry, coordinated logistics, and a willingness to absorb the administrative systems of the peoples they conquered. The empire eventually fractured into separate khanates, but for a time it connected trade and communication across Asia and Europe more directly than at any point before, moving goods, ideas, and unfortunately diseases along the Silk Road.