Ever since man believed that the earth was round, the belief that other lands existed became the norm.
Even though the belief that a "great southern land" existed, there was no way of finding it. The technology needed would not be invented for almost 2,000 years.
Greek philosophers handed down their beliefs of "Terra Australis" existence to the Romans, together with the art of map-making. The belief filtered through to Europe and continued on right up to the middle-ages, enforced by writers like Cicero and Pliny.
During the middle ages in Europe, a sudden return to the belief that the world was flat returned. "Common-sense" arguments were used to conclude that the earth really was flat. Geographers based their conclusions on scriptures arguing that the world "must be flat" giving many and varied arguments as to why this was so. Opinions were based on religious teaching instead of cold hard facts. Geographer Cosmas Indicopleustes (547 A.D.) argued "The world was certainly flat" because (according to him) "the Tabernacle built by Moses was the pattern of the world". Arguments like this proved convincing setting back any hope of new discoveries for hundreds of years to come.
Despite these setbacks, in the end (around 1270 A.D.) the Greek belief was on its way back. In Europe mystic tales of Marco Polo and his travels to the East were spreading fast. A Venetian adventurer, Polo had spent 24 years travelling from country to country undertaking a series of great adventures. For a long time he lived in Peking at the Court of the Great Khan. He became a state official and was given important tasks to perform for the Khan. He took charge of transporting a Chinese princess to Persia returning to Venice with untold riches and many fantastic stories.
Travel guides became increasingly popular throughout Europe. In today's terms, Marco's books would be considered best-sellers. It was his many tales of previously untold riches and exciting new discoveries that played a big part in creating the neccessary atmosphere of discovery later abundant in Europe.
One of Marco's books, the story of Marco's voyage from China to Persia penned by his friend and companion, holds an account of Marco's travels to Thailand. In the book, Thailand is mistakenly described as the "Great South Land" with stories of untold wealth just waiting to be taken. Of course this inspired many to re-think previous thoughts and the idea totally re-generated. There really was a great south land, a Continent larger than any found before. The biggest problem would be, how could anybody travel so far and be guaranteed a good chance of return?...