The line between Europe and Asia was drawn by one 18th-century mapmaker

There's no geological reason Europe and Asia count as separate continents rather than one Eurasian landmass. The convention traces to Swedish geographer Philip Johan von Strahlenberg, who proposed the Ural Mountains as the dividing line in 1730 for want of a clearer natural feature. Mapmakers adopted his boundary, and it still defines the continental split used in atlases today.

— Standard geographic accounts, Ural Mountains — Boundary proposed by Philip Johan von Strahlenberg, 1730