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.
History of Czechoslovakia
On 14 March 1939, the Slovak State declared its independence as a satellite state under Jozef Tiso. Hitler forced Hácha to surrender what remained of Bohemia and Moravia to German control on 15 March 1939, establishing the German Protectorate of Bohemia and Moravia. On the same day, the Carpatho-Ukraine (Subcarpathian Ruthenia) declared its independence and was immediately invaded and annexed by Hungary. Finally, on 23 March, Hungary invaded and occupied some further parts of eastern Slovakia from Carpatho-Ukraine.