A successor state is a concept in international relations regarding a sovereign state that has formed over a territory and populace that was previously under the sovereignty of another state. A successor state often acquires a new international legal personality, which is distinct from a continuing state, also known as a continuator or historical heir, which despite changes to its borders retains the same legal personality and possess all its existing rights and obligations (such as a rump state).[1] The theory has its roots in 19th-century diplomacy.[2]