Karelia is on the medieval Europe's map
The earliest known us maps of the Europe with drawn name "Carelia" were composed by Swedish Catholic bishop Olaus Magnus (1490-1558) in XVI century.
Carta Marina was issued by Magnus as wall-map in 1539. The large lake in the north-eastern corner of the map - Ladoga Lake - was united with the White Sea in whole.
The first issue of History of Northern people (Historia Gentibus septentrionalibus) appeared in 1555. Here is a part of Magnus's map from Italian reprint of this book in 1565.