The Tokugawa government distrusted foreigners mainly because it feared that outside influence—especially Christianity and European political ambitions—would undermine its political control, social order, and cultural traditions.

Core reasons for distrust

  • The shogunate believed that foreign powers, particularly European states, used missionaries and trade as a first step toward colonization, as had happened in parts of Asia and the Americas.
  • Christianity was seen as a direct threat to loyalty toward the shogun, since converts might prioritize allegiance to a foreign faith and foreign leaders over Japan’s established political and religious hierarchy.
  • The Tokugawa rulers had just unified Japan after a long era of civil war and worried that foreign weapons, ideas, or alliances could reignite internal conflict.

Sakoku and keeping control

  • In response, the Tokugawa regime created the sakoku (“closed country”) system in the 17th century, sharply restricting foreign trade and contact to tightly controlled channels such as Nagasaki.
  • Edicts in the 1630s banned most Europeans, expelled missionaries, and forbade Japanese people from leaving the country or returning from abroad, so potentially “foreign-influenced” subjects could not re-enter society.

Christianity and rebellion

  • Anti-Christian policies intensified after events like the Shimabara Rebellion (1637–1638), in which many rebels were Christian peasants; this reinforced the shogunate’s view that foreign religion could inspire armed resistance.
  • As a result, the government equated foreign religious presence with potential sedition and doubled down on persecution and exclusion of Christian influence.

Protecting social order and culture

  • The Tokugawa system relied on a rigid social hierarchy (samurai, peasants, artisans, merchants); foreign merchants and new ideas about trade, money, and status threatened to blur these lines.
  • Foreign cultural influence was also seen as dangerous to Confucian -based norms and traditional authority, so limiting contact was a way to preserve Japanese customs, values, and the prestige of the shogunate.

Limited exceptions, deep suspicion

  • The shogunate allowed only very controlled relationships with a few groups—such as Dutch and Chinese traders at Nagasaki—because they provided useful goods and knowledge without (in Tokugawa eyes) aggressively pushing religion.
  • Even these exceptions operated under strict surveillance, showing that the core attitude remained one of suspicion: foreigners were tolerated only when they could be tightly managed and kept politically harmless.

TL;DR: The Tokugawa government distrusted foreigners because they associated them with Christianity, colonization, rebellion, and disruptive new ideas that could destabilize their carefully constructed political and social order.