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.
Slovakia during World War II
The desire for autonomy was one of the great issues of Slovaks in Czechoslovakia. Josef Tiso and nationalists of the Slovak People's Party pushed for Slovak independence and aligned themselves with the National Socialist Party in Germany. On March 13, 1939 Hitler invited Tiso to Berlin. Hitler would support him if he separated Slovakia from Czechoslovakia or the Slovakia territory will be divided under Hungary, Czech Republic and Poland. On March 14, 1939 Slovakia declared independence, calling itself the Slovak Republic. German troops soon occupied Bohemia and Moravia.