Thirteenth-century Japan has this in common with early 19th-century Japan: a land culture paying scant heed to the sea until the sea, as though in outrage, rises up and compels attention.

The dominant features of 13th-century Japan are Zen Buddhism and the newly empowered samurai; of early 19th-century Japan, Confucianism and sakoku — the country closed to the outside world. In the earlier period, only fishermen and pirates are afloat; in the later, them and the occasional castaway.

A 13th-century samurai, rigorously trained to an ascetic view of life, would have been astonished to read the dazzled fantasies his contemporary, the great Venetian traveler Marco Polo, was spinning about Japan.