Sakoku, meaning 'closed country,' refers to the period of isolationist foreign policy enacted by Japan during the Edo period from the early 17th century until the mid-19th century. This policy severely restricted foreign influence and trade, with strict regulations governing interactions with outsiders, effectively limiting Japan's contact with the rest of the world. It was a response to the perceived threats from European powers and Christianity, shaping Japan's social, political, and economic landscape during this time.