Final answer:
Columbus proposed sailing West to reach Asia to avoid the perilous land routes and the long voyage around Africa, as the spherical shape of the Earth would allow for this alternative path. Securing funding from Spain, he embarked on voyages that ultimately led to the discovery of the New World.
Step-by-step explanation:
Christopher Columbus proposed sailing West to reach the East Indies because the overland routes were perilous and the voyage around Africa posed significant challenges. Columbus knew the Earth was round and believed that by sailing west, he could find a quicker and safer passage to Asia, thus capitalizing on the lucrative spice trade.
Moreover, the collapse of the Mongol Empire had made the land route to Asia more dangerous and expensive, leading to an increased interest in finding a sea route. With Portugal focusing on the southern route around Africa, Columbus turned to Spain. After securing funding from King Ferdinand and Queen Isabella, he embarked on his voyages, which inadvertently led to the discovery of the New World.