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.
Second Czechoslovak Republic
The Czechoslovak Republic was dissolved when Germany invaded it on 15 March 1939 and annexed the Czech region into the Protectorate of Bohemia and Moravia. On the same day as the German occupation, the President of Czechoslovakia, Emil Hácha was appointed by the German government as the State President of the Protectorate of Bohemia and Moravia which he held throughout the war.