Harem, properly refers to domestic spaces that are reserved for the women of the house in a Muslim family. This private space has been traditionally understood as serving the purposes of maintaining the modesty, privilege, and protection of women. A harem may house a man's wife or wives, their pre-pubescent male children, unmarried daughters, female domestic workers, and other unmarried female relatives. In royal harems of the past, concubines of the prince were also housed in the harem. In former times some harems were guarded by eunuchs who were allowed inside. The structure of the harem and the extent of monogamy or polygamy has varied depending on the family's personalities, socio-economic status, and local customs. Similar institutions have been common in other Mediterranean and Middle Eastern civilizations, especially among royal and upper-class families, and the term is sometimes used in other contexts. In traditional Persian residential architecture the women's quarters were known as andaruni (Persian: اندرونی; meaning inside, and in the Indian subcontinent as zenana.