Classical Islamic jurisprudence prohibited voluntary travel to non-Muslim lands.

Evidence

These were people to whom it had been virtually inconceivable that one would go by one’s own choice to an infidel country. In the past it was universally agreed among the juristic authorities of Islam that it was a bad thing for Muslims to go to a country ruled by non-Muslims. The usual view was that such a thing was categorically prohibited; that Muslims must not go to a non- Muslim country voluntarily. Some allowed it in certain narrowly-defined circumstances—to redeem captives, to go on a mission to negotiate the redemption of captives and perhaps to buy supplies in times of dearth or of critical shortage. — Bernard Lewis, From Babel to Dragomans, 743

Categorization

• XREF: The legal prohibition on entering Dar al-Harb parallels the inverse asymmetry that Orientalist travel writing installed; useful for mapping early-19th-century reversed migration against Said’s framework.
• DEFINE: Grounds the Dar al-Islam / Dar al-Harb division in concrete legal consequences for travel, not just abstract geography.