There are a number of synonyms for the phrase "walled off" that express the notion of being enclosed or separated from something. One such synonym might be "isolated," which implies a sense of being cut off and disconnected. Another possible synonym could be "encased," which connotes a more physical sense of being surrounded by a shell or barrier. Other potential synonyms might include "sequestered," "insulated," or "quarantined." These words all suggest a sense of being removed from some external influence, whether that is a physical barrier or a social or cultural one. Ultimately, the choice of synonym will depend on the context and intended meaning of the phrase.