Hello Hanuman It's an inverted passive sentence. Sometimes in a passive sentence the subject and the verbial (past participle) are inverted to avoid too heavy a subject, though the subject ('the map of Japan') in your sentence is rather short. type=INVVIIUI "]Grammar Station (INVERSION)[/url].
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.