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.
Czechoslovakism
Repeated ľudák's autonomy demands were accepted by the Czechoslovak parliament in November 1938, in wake of major European political turmoil caused by German territorial demands versus Czechoslovakia and when the southern belt of Slovakia was about to be handed over to Hungary. In aftermath of the Sudetenland crisis and fearing total breakup of the country, the Czech deputies consented to the Slovak draft. Slovakia became a fully autonomous unit with own government, administration and special budgetary provisions; some overall Czechoslovak issues, e.g. presidential elections, were subjected to consent of qualified majority of the Slovak assembly. The constitutional amendment abandoned the original concept of Czechoslovak nation and referred to Czech and Slovak nations; the country was renamed from Czechoslovak to Czecho-Slovak Republic. This setup lasted only few months; in March 1939 the prime minister of autonomous Slovakia and the ľudák leader Jozef Tiso declared total independence. At the time Czech lands were overrun by German troops and soon got incorporated into the Reich as Protectorate of Bohemia and Moravia.