Later it was considered as working from the Black Sea via Kerch Strait, the Sea of Azov and alongside the Don River in Russia. The boundary between Asia and Africa was typically taken to be the Nile River. Herodotus within the 5th century BC objected to the entire of Egypt being break up between Asia and Africa (“Libya”) and took the boundary to lie alongside the western border of Egypt, concerning Egypt as part of Asia. He also questioned the division into three of what is really a single landmass, a debate that continues almost two and a half millennia later. The most restricted meaning of continent is that of a continuous[non-tertiary supply needed] area of land or mainland, with the coastline and any land boundaries forming the sting of the continent. Similarly, the continental United States refers back to the 48 contiguous states and the District of Columbia and should include Alaska in the northwest of the continent , whereas excluding Hawaii in the Pacific Ocean.
On the west coast of North America, the principle rivers are the Colorado River, Columbia River, Yukon River, Fraser River, and Sacramento River. In 1501, Amerigo Vespucci and Gonçalo Coelho tried to sail round what they thought-about the southern end of the Asian mainland into the Indian Ocean, passing by way of Fernando de Noronha. After reaching the coast of Brazil, they sailed a good distance farther south along the coast of South America, confirming that this was a land of continental proportions and that it also extended a lot farther south than Asia was identified to. On return to Europe, an account of the voyage, called Mundus Novus (“New World”), was revealed beneath Vespucci’s name in 1502 or 1503, though plainly it had additions or alterations by one other author. In many of those circumstances, the “subcontinents” concerned are on different tectonic plates from the relaxation of the continent, offering a geological justification for the terminology. Greenland, usually reckoned as the world’s largest island on the northeastern periphery of the North American Plate, is usually known as a subcontinent.