Simplify the following text for a Grade 7 native English-speaking person.
Original: Belief in the existence of a Terra Australis â `` a vast continent in the far south of the globe to `` balance '' the northern lands of Europe , Asia and North Africa â `` has existed since the times of Ptolemy ( 1st century AD ) , who suggested the idea to preserve the symmetry of all known landmasses in the world .
Simplified: They thought this Terra Australis would `` balance '' the lands in the north like Europe , Asia and North Africa . People have believed this from the times of Ptolemy ( 1st century AD ) .