insular

This term carries a strong connotation of narrow-mindedness when applied to people or societies. It suggests a psychological barrier where a lack of exposure to external perspectives leads to a rigid, often arrogant, adherence to local customs or beliefs. In a geographical or physical sense, it describes the literal state of being an island. This physical isolation serves as the root for the word's metaphorical meaning, linking the physical separation of land by water to the mental separation of ideas by prejudice or ignorance.