Sakoku refers to the period of Japan's self-imposed isolation from the 1630s to the mid-19th century, during which the country restricted foreign influence and trade, allowing only limited interactions with specific nations. This policy was primarily aimed at maintaining social order and preserving Japan's cultural identity in the face of European imperial expansion and missionary activities. The isolationist stance played a significant role in shaping Japan's eventual response to modernization and state-led industrialization when it finally opened up to the world.