A harem is a domestic space that is reserved for the women of the house in a Muslim family. A harem may house a man's wife or wives, their pre-pubescent male children, unmarried daughters, female domestic servants, and other unmarried female relatives. In the past, during the era of slavery in the Muslim world, harems also housed enslaved concubines. In former times, some harems were guarded by eunuchs who were allowed inside. The structure of the harem and the extent of monogamy or polygyny have 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, and in the Indian subcontinent as zenana.