The Balkan Entente is formed between Greece, Romania, Yugoslavia, and Turkey.

The Balkan Pact, or Balkan Entente, was a treaty signed by Greece, Romania, Turkey and Yugoslavia on 9 February 1934 in Athens, aimed at maintaining the geopolitical status quo in the region after the end of World War I. To present a united front against Bulgarian designs on their territories, the signatories agreed to suspend all disputed territorial claims against one another and their immediate neighbours following the aftermath of the war and a rise in various regional irredentist tensions.

The Kingdom of Greece was the Greek nation-state established in 1832 and was the successor state to the First Hellenic Republic. It was internationally recognised by the Treaty of Constantinople, where Greece also secured its full independence from the Ottoman Empire after nearly four centuries. It remained a Kingdom until 1924, when the Second Hellenic Republic was proclaimed, and from the Republic's collapse in 1935 to its dissolution by the Regime of the Colonels in 1973. A referendum following the regime's collapse in 1974 confirmed the effective dissolution of the monarchy and the creation of the Third Hellenic Republic. For much of its existence, the Kingdom's main ideological goal was the Megali Idea, which sought to annex lands with predominately Greek populations.

The Kingdom of Romania was a constitutional monarchy that existed from 25 March [O.S. 13 March] 1881 with the crowning of prince Karl of Hohenzollern-Sigmaringen as King Carol I, until 1947 with the abdication of King Michael I and the Romanian parliament's proclamation of the Romanian People's Republic.

The Kingdom of Yugoslavia was a country in Southeast and Central Europe that existed from 1918 until 1941. From 1918 to 1929, it was officially called the Kingdom of Serbs, Croats, and Slovenes, but the term "Yugoslavia" has been its colloquial name as early as 1922 due to its origins. The official name of the state was changed to "Kingdom of Yugoslavia" by King Alexander I on 3 October 1929.