South America dwarfs Thailand: about 17,840,000 km² km² against 515,720 km² km². At true size South America is about 34.6× larger — the whole of Thailand fits into South America roughly 34 times.
The old Mercator map treated both about equally (1× vs 1.1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Thailand fits 34× into South America.