Suzerainty (/ˈsjuːzərənti/ or /ˈsjuːzərɛnti/) is a situation in which a powerful region or people controls the foreign affairs of a tributary vassal state while allowing the subservient nation internal autonomy. The dominant entity in the suzerainty relationship, or the more powerful entity itself, is called a suzerain. The term suzerainty was originally used to describe the relationship between the Ottoman Empire and its surrounding regions. It differs from sovereignty in that the tributary enjoys some (often limited) self-rule.A suzerain can also refer to a feudal lord, to whom vassals must pay tribute. Although it is a concept which has existed in a number of historical empires, it is a concept that is very difficult to describe using 20th- or 21st-century theories of international law, in which sovereignty either exists or does not. While a sovereign nation can agree by treaty to become a protectorate of a stronger power, modern international law does not recognize any way of making this relationship compulsory on the weaker power.