Myanmar dwarfs Oceania: about 662,746 km² km² against 8,600,000 km² km². At true size Myanmar is about 13× larger — the whole of Oceania fits into Myanmar roughly 12 times.
The old Mercator map treated both about equally (1.2× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Myanmar fits 12× into Oceania.