Eurasia is the largest continental area on Earth, comprising all of Europe and Asia. According to some geographers, physiographically, Eurasia is a single supercontinent. The concepts of Europe and Asia as distinct continents date back to antiquity, but their borders have historically been subject to change. For example, to the ancient Greeks, Asia originally included Africa but they classified Europe as separate land. Eurasia is connected to Africa at the Suez Canal, and the two are sometimes combined to describe the largest contiguous landmass on Earth, Afro-Eurasia.