In 1588, the Spanish Armada was defeated. Which Asian power was beginning a long period of isolation?

The story behind the answer

Tokugawa Japan is correct. Just after this period, Japan unified under Tokugawa Ieyasu (1603), and his successors enacted sakoku (“closed country”) policies in the 1630s. For over two centuries, Japan tightly controlled foreign contact—limiting trade mainly to the Dutch and Chinese at Nagasaki’s Dejima—until Commodore Perry forced openings in the 1850s.

Why not the others? The Ming still traded widely in the late 1500s; Joseon Korea maintained tributary ties and diplomacy; the Sikh Empire didn’t yet exist. Memory tip: Think “Armada near the age of Edo”—Spain’s naval fall coincides with the dawn of the Tokugawa era, when Japan “tucked in” behind closed doors.