Danubian Principalities Danubian Principalities ( , ) was a conventional name given to the Principalities of Moldavia and Wallachia , which emerged in the early 14th century . The term was coined in the Habsburg Monarchy after the Treaty of Küçük Kaynarca ( 1774 ) in order to designate an area on the lower Danube with a common geopolitical situation . The term was largely used then by foreign political circles and public opinion until the union of the two Principalities ( 1859 ) . Alongside Transylvania , the United Principalities of Moldavia and Wallachia became the basis for the Kingdom of Romania , and by extension the modern Romania n nation - state . In a wider context , the concept may also apply to the Principality of Serbia in terms of " The Principalities of the Danube " which came under the suzerainty ( alongside Wallachia and Moldova ) of the Porte from 1817 . History . Early history . The two emerged as vassals of the Hungarian Crown ( in the case of Wallachia , Hungarian suzerainty had been present for the polities which preceded the unifying rule of Basarab I ) , and remained so until their independence ( 1330 for Wallachia and 1359 for Moldavia ) . In 1476 Wallachia and in 1538 Moldavia came under initially formal Ottoman suzerainty ; however , they preserved their self - rule in all aspects but foreign affairs , except for periods when individual princes defied Ottoman suzerainty and established extensive foreign relations as well — one such rule , that of Michael the Brave , also brought a brief personal union of the Danubian Principalities with each other and with Transylvania in 1600 . After a marked decline in independence and prosperity over the 16th and 17th centuries ( directly linked to the demands of the Porte during the Stagnation of the Ottoman Empire ) , further independent and insurgent rules , which connected the two countries with Habsburg and Russian Empire offensives during the Great Turkish War , were blocked by the Ottomans by the introduction of Phanariote rules over the two countries — 1711 in Moldavia and 1714 in Wallachia ) . These , while connected with the very first administrative reforms , generally had to rely on spoliation , and coincided with a disastrous stage in the countries ' history , given that the two became a major theatre of war in a series of confrontations between Russian , Habsburg , and Ottoman forces ( until the mid - 19th century , they frequently came under temporary Russian or Habsburg occupation , and sometimes administration — as happened to the regions of Oltenia , Bukovina , and Bessarabia ) . The high taxation , reprimations , wars and pillaging during this hundred years led to a substantial deterioration of the quality of economical and cultural life , and to a decrease of population by 30 % . ( The following century the population would quadruple , and in 20th century would increase by another 50 % . ) Early 19th century . The two countries became connected with the cause of Greek independence during the Greek Independence War : the Filiki Eteria , backed by most Phanariotes , maneuvered in Moldavia , while the 1821 Wallachian uprising combined anti - Phanariote sentiment with an allegiance to the Eteria - ultimately , these two aspects came into conflict inside the movement itself , and Wallachian initiative was toppled by an Eteria administration which had to retreat in the face of Ottoman invasion . Although these events brought about the disestablishment of Phanariote rules by the Porte itself , this was of little consequence in itself , as a new Russo - Turkish War brought a period of Russian occupation under formal Ottoman supervision , extended between 1829 and the Crimean War . A parallel Russian military administration was put in place , while the two principalities were given the first common governing document ( the " Organic Statute " ) : although never fully implemented , it confirmed a modernizing government , created a new legal framework that reformed public administration , and deeply influenced political life in the following decades . The Russian pressures for changes in the text were perceived by Wallachians and Moldavians as a drive to remove the territories from Ottoman rule and annex them to a much more centralised and absolutist empire . This coincided with the period of national awakening and the Revolutions of 1848 - the rejection of Russian tutelage during the Moldavian attempt and the Wallachian revolutionary period were viewed with a degree of sympathy by the Porte , but calls by Russia ultimately led to a common occupation in the years following the rebellion ' s crushing . United Principalities . The aftermath of Russian defeat in 1856 ( the Treaty of Paris ) brought forth a period of common tutelage of the Ottomans and a Congress of Great Power s ( the United Kingdom of Great Britain and Ireland , the Second French Empire , the Kingdom of Piedmont - Sardinia , the Austrian Empire , Prussia , and , albeit never again fully , Russia ) . While the Moldavia - Wallachia unionist cause , which had come to dominate political demands , was viewed with sympathy by the French , Russians , Prussians , and Sardinians , it was rejected by the Austrian Empire , and viewed with suspicion by Great Britain and the Ottomans . Negotiations amounted to an agreement over a minimal and formal union - however , elections for the " ad hoc divan s " of 1859 profited from an ambiguity in the text of the final agreement ( specifying two thrones , but not preventing the same person from occupying both ) and made possible the rule of Alexander Ioan Cuza as " Domnitor " of the United Principalities of Moldavia and Wallachia ( of Romania from 1862 ) . Although internationally recognized only for the period of Cuza ' s rule , the union was cemented by Cuza ' s unsanctioned interventions in the text of previous organic law s , as well as by the circumstances of his deposition in 1866 , when the rapid election of Carol of Hohenzollern - Sigmaringen , who had the backing of an increasingly important Prussia , and the Austro - Prussian War made measures taken against the union impossible . In 1878 , after the Romanian War of Independence , Romania shook off formal Ottoman rule , but clashed with its Russian ally over the Russian request for the Bujak ( southern Bessarabia ) - ultimately , Romania was awarded Northern Dobruja in exchange for southern Bessarabia . A Kingdom of Romania emerged in 1881 .