Asia dwarfs Mongolia: about 44,580,000 km² km² against 1,560,428 km² km². At true size Asia is about 28.6× larger — the whole of Mongolia fits into Asia roughly 28 times.
The old Mercator map treated both about equally (1× vs 2.2× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Mongolia fits 28× into Asia.