Both countries share 443 km (275 mi) of common border and are full members of NATO and the European Union; however, despite current alliances, there are historical national tensions over Transylvania.

The Hungarian tribes originated in the vicinity of the Ural Mountains and arrived in the territory formed by present-day Romania during the 9th century from Etelköz or Atelkuzu (roughly the space occupied by the present day Southern Ukraine, the Republic of Moldova and the Romanian province of Moldavia).

The ethnic Romanian elected representatives of Transylvania, Banat, Crișana and Maramureș proclaimed Union with Romania on 1 December 1918.

With the conclusion of World War I, the Treaty of Trianon (signed on 4 June 1920) defined the new border between the states of Hungary and Romania.

[15] Also after World War I, a group of Csángó families founded a village in Northern Dobruja known as Oituz, where Hungarians still live today.

The Treaty of Paris (1947) after the end of the Second World War overturned the Vienna Award, and the territory of northern Transylvania was returned to Romania.

Today, "Transylvania proper" (bright yellow on the accompanying map) is included within the Romanian counties (județe) of Alba, Bistrița-Năsăud, Brașov, Cluj, Covasna, Harghita, Hunedoara, Mureș, Sălaj (partially) and Sibiu.

The Romanians were forced to retreat to the historical region of Moldavia, but were able to stave off complete collapse in 1917 by reorganizing their army and repulsing the Central Powers' offensive at Mărășești and Oituz.

Nevertheless, after the October Revolution of 1917, Russia fell into civil war, and the Russian government signed two ceasefire agreements with the Central Powers, followed later (on 15 December) by a full armistice.

Lacking Russian support, the Romanian government was subsequently forced to sue for peace, concluding in December 1917 the Armistice of Focșani.

Moreover, the Hungarian government swung then more and more to the right; eventually, under Regent Miklós Horthy, Hungary established close relations with Benito Mussolini's Fascist Italy and Adolf Hitler's Nazi Germany.

These politics and the sought for revision succeeded to regain the territories of southern Czechoslovakia by the First Vienna Award in 1938 and the annexation of the remainder of Subcarpathia in 1939.

In 1940, the Soviet occupation of Bessarabia and Northern Bukovina inspired Hungary to escalate its efforts to resolve "the question of Transylvania".

Soon after the demise of the Communist regimes in Hungary and Romania, in March 1990, violent ethnic clashes in Transylvania strained the relationship between both countries to the brink of war.

As a result, the first Open Skies Treaty in the world to mutually assess the strength and disposition of opposing military forces was worked out and became effective in 1992.

In 1996, Romania signed and ratified a basic bilateral treaty with Hungary that settled outstanding disagreements, laying the foundation for closer, more cooperative relations.

[33][34] Wizz Air is a low-cost airline from Hungary, which operates flights from several airports in Romania (Bucharest, Cluj-Napoca, Târgu Mureș, Sibiu, Timișoara, Iasi, Suceava and Craiova) to various destinations in Europe.

[39] The exit and sale was reported due to Digi was not only excluded from taking part in an auction for 5G access in Hungary but subsequently lost a court case against the Hungarian regulator NMHH.