The United Principalities of Moldavia and Wallachia, commonly called United Principalities or Wallachia and Moldavia, was the personal union of the Principality of Moldavia and the Principality of Wallachia. The union was formed on 5 February [O.S. 24 January] 1859 when Alexandru Ioan Cuza was elected as the Domnitor of both principalities. Their separate autonomous vassalage in the Ottoman Empire continued with the unification of both principalities. On 3 February [O.S. 22 January] 1862, Moldavia and Wallachia formally united to create the Romanian United Principalities or Romania the core of the Romanian nation state.