Ten countries joined the EU on one day, 1 May 2004
On 1 May 2004 ten states joined the European Union together, under the Treaty of Accession signed in Athens in 2003. It is the largest single enlargement the union has had. Eight of the ten were formerly communist states of central and eastern Europe, and three of those eight were former Soviet republics on the Baltic. The other two were Mediterranean island states. The list is fixed: nothing that happens now can add to it or take from it.
Name all ten first. Then sort them into their three groups.