Slovakia
The Slovak Republic and the Czech Republic went their separate ways after 1 January 1993, an event sometimes called the Velvet Divorce. Slovakia has remained a close partner with the Czech Republic. Both countries co-operate with Hungary and Poland in the Visegrád Group. Slovakia became a member of NATO on 29 March 2004 and of the European Union on 1 May 2004. On 1 January 2009, Slovakia adopted the Euro as its national currency.
Czechoslovakia–Poland relations
Czechoslovakia gained independence in the aftermath of World War I, as Austria-Hungary fell apart, just as Poland regained independence as the Second Polish Republic after 123 years of partitions. Both emerging countries shared a long border, and soon became enveloped in a border conflict. Although it never developed into an open war, this conflict led to uneasy relations between both states in the interwar period.