Africa
Africa is a continent directly to the south of Europe. Little was known of its extent during the Middle Ages, and it was assumed that it blocked off a sea route to India from the West. In medieval cartography the so called T-O maps showed Africa as roughly the same size as Europe, but with everything East of the Nile being part of Asia.
In the 15th century, Vasco da Gama eventually found the route around Africa and its full size was appreciated.
Functionally, the Roman Empire treated Africa down to the Sahara (plus the Nile valley) as an appenage to the Empire, and a source of slaves, extoic beasts, strange gems, and (in the case of Egypt) most of Rome's grain crop.
Post Rome the same attitude persisted, because the Eastern Roman Empire (Byzantium) sought to retain much of North Africa under its aegis, and first the Christians and then the Muslims spread along the Mediterranean coast, selling their faiths.
Below the Sahara, the only bit of Africa known to medieval Europe was the kingdom of Ethiopia (later to be adapted to become the semi-mythical kingdom of Prester John). Arab traders did attempt the western coastline, but unfortunately the records of their voyages have perished, allowing later Western explorers to claim credit for the same discoveries. Again, in the main, the interest was in acquiring exotic trading goods and slaves -- no-one appears to have considered that there were fully functional kingdoms and empires in them thar jungles -- civilizations which rose and fell, and the last ones of which were extinguished when the English swept through Africa bringing civilization and disease, and stripping out any vestige of wealth they could find, whilst parcelling the land out to their own colonists, with hot and cold running labourers provided on site (all very medieval, of course).
