Ghettos began partly as Jewish self-protection, not only imposed confinement.

Evidence

There has been a long-standing tendency of Jews, like other foreign groups, to seek to live together, both for convenience and protection. Sometimes Jews sought the assistance of the secular authorities in securing for themselves an enclosed area of the city. At a time when cities were often divided into separate districts by gated areas, Jews wanted their own secured residential quarter to protect them against violence and threats of violence arising from the growth in antisemitism. The Church authorities also had an interest in separating the Jews from ordinary Christians. In 1179 the Third Lateran Council decreed that Christians who lived in proximity to Jews should be excommunicated from the Catholic Church. This reflected a growing fear within the Church hierarchy that the faith of ordinary Christians might be contaminated by close contact with Jews. Similar concerns were directed against Saracens. — David Theo Goldberg, John Solomos, A Companion to Racial and Ethnic Studies, 2370

Categorization

• XREF: The voluntary-safe-enclave origin complicates the standard imposed-confinement reading, echoing self-segregation dynamics seen in immigrant clusters elsewhere.
• QUESTION: Worth chasing: how much of early ghetto formation was cooperative between Jews and authorities versus purely coerced, and how the Church’s excommunication decree fits the wider picture.