What does "immigrant enclave" mean?

Enclave is a special phenomenon of human geography.

Enclave is a special phenomenon of human geography, which refers to the land under the jurisdiction of an administrative region but not adjacent. If an administrative subject owns an enclave, it can't reach it through its own administrative area, and it can only reach its own enclave by "flying over" the territory of other administrative subjects.

The concept of enclave originated in the Middle Ages, and the word first appeared in the document of Madrid Treaty signed by 1526. The historical causes of enclaves are quite complex, with some characteristics of marginal zones, relatively weak government control, lax management and high cost; Social economy is relatively backward and cultural diversity is rich.