Czech Republic–Slovakia relations
Before 1918, both countries were part of Austria–Hungary. However, after the Ausgleich of 1867 Czechia belonged to the Austrian Empire while Slovakia belonged to the administratively separate Kingdom of Hungary, and between 1918 and December 31, 1992, both countries were part of Czechoslovakia. 
Both countries established diplomatic relations on January 1, 1993. These international relations are usually referred to or described as "very good", "cordial", and "above standard" in the media. When a Czech or Slovak president is inaugurated, very often his first international visit is to the former part of the common country. The same custom applies to newly elected prime ministers of the Czech Republic and Slovakia.
Tanks of Czechoslovakia
After the first World War, Slovakia and the regions of Bohemia, Moravia, Silesia and Carpathian Ruthenia formed a common state, Czechoslovakia, with the borders confirmed by the Treaty of Saint Germain and Treaty of Trianon. In 1919, during the chaos following the breakup of Austria-Hungary, Czechoslovakia was formed with numerous Germans and Hungarians within the newly set borders. A Slovak patriot Milan Rastislav Štefánik (1880–1919), who helped organize Czechoslovak regiments against Austria-Hungary during the First World War, died in a plane crash. In the peace following the World War, Czechoslovakia emerged as a sovereign European state. It provided what were at the time rather extensive rights to its minorities and remained the only democracy in this part of Europe in the interwar period.