Archaeological remains dating from the Hallstatt period have been found, particularly in southeastern Slovenia, among them a number of situlas in Novo Mesto, the "Town of Situlas".
The area that is present-day Slovenia was in Roman times shared between Venetia et Histria (region X of Roman Italia in the classification of Augustus) and the provinces Pannonia and Noricum.
Patria del Friuli ruled present western Slovenia until Venetian takeover in 1420.
At the end of the Middle Ages, the Slovene Lands suffered a serious economic and demographic setback because of the Turkish raids.
A crucial battle between Theodosius I and Eugenius took place in the Vipava Valley in 394.
They were mostly christianized by Irish missionaries, among them Modestus, known as the "Apostle of Carantanians".
This process, together with Christianization of Bavarians, was later described in the memorandum known as the Conversio Bagoariorum et Carantanorum, which is thought to have over-emphasized the role of the Church of Salzburg in the Christianization process over similar efforts of the Patriarchate of Aquileia.
Afterward, it was a founding member of the Federal People's Republic of Yugoslavia, later renamed the Socialist Federal Republic of Yugoslavia, a communist state which was the only country in the Eastern Bloc which was never part of the Warsaw Pact.
In June 1991, after the introduction of multi-party representative democracy, Slovenia split from Yugoslavia and became an independent country.