In an attempt to expand its territory further north, the Roman Empire reached the Danube River in southeastern Europe in 100 AD, and established the new province of Roman Dacia.
As the Roman Empire began its decline in the late 2nd century, Dacia was invaded by the Goths, an East Germanic tribe of Scandinavian origin. Over the next five centuries a wide variety of migrating people crossed through.
In the 8th century, the Avars, a highly organized nomadic confederacy of mixed origins conquered the land, and ruled the remaining Slavic serfs in the Transylvania region until the 8th century.
In the High to Late Middle Ages, from the Black Sea coastal areas through the mountainous central, and to the western borders of what is now modern-day Hungary and Serbia, Romania was occupied by an assortment of nomadic peoples.
By the middle of the 16th century, Hungary, and most of the Balkan Peninsula including Romania's historical regions of Moldavia (northeast), Transylvania (central) and Wallachia (in the south) were under varied levels of Ottoman (Turkish) control.
Near the end of the 17th century, a league of factions (including the Hapsburg) organized by Pope Innocent XI, was sent to free Hungary from Ottoman rule and reinstate the Catholic Church. That effort stretched into Romania, and in 1699, Transylvania became a territory of the Habsburgs' Austrian empire.
The Habsburgs were one of the most important aristocratic royal houses of Europe, best known for being the origin of all of the formally elected Holy Roman Emperors between 1438 and 1740. Within a few short years the Hapsburg's occupied other small parts of Moldavia and Wallachia.
The European Revolutions of 1848 were a series of political upheavals throughout the continent. They were caused by widespread dissatisfaction with leadership; the demands of the working classes and a growing upsurge of nationalism in individual countries and regions.
It was the first (and only) Europe-wide collapse of traditional authority. During the revolutions tens of thousands of people were killed and many more forced into exile, and within one year, the powerful reactionary forces (of royalty) had won out and the revolutions collapsed.
After the failed 1848 Revolution, Romanians wanted to form a single state, but that struggle was squelched by the Austria-Hungary empire, as it kept the Romanians firmly in control, even in parts of Transylvania where Romanians constituted a local majority.
During the Russo-Turkish War of 1877–1878 between the Ottoman Empire and the Eastern Orthodox coalition led by the Russian Empire and numerous Balkan countries, Romania fought on the Russian side, and that was a good decision.
Within the 1878 Treaty of Berlin between the two warring parties, Romania was recognized as an independent state (principality) by Russia and some other European powers of the day. To make the deal Romania ceded some land along its eastern border to Russia.