In , the Communities were enlarged to include Denmark including Greenland , which later left the Communities in , following a dispute over fishing rights , Ireland , and the United Kingdom. Nevertheless, in an agreement was reached and on 1 July the Merger Treaty created a single set of institutions for the three communities, which were collectively referred to as the European Communities. Since then, the eurozone has increased to encompass 19 countries. In , euro banknotes and coins replaced national currencies in 12 of the member states. The expansion of the EU introduced a new level of complexity and discord. During the centuries following the fall of Rome in , several European States viewed themselves as translatio imperii of the defunct Roman Empire: The same year, Slovenia adopted the euro,  followed in by Cyprus and Malta , by Slovakia in , by Estonia in , by Latvia in , and by Lithuania in They also signed another pact creating the European Atomic Energy Community Euratom for co-operation in developing nuclear energy. Euratom was to integrate sectors in nuclear energy while the EEC would develop a customs union among members. In , the later gave a famous speech in favour of a European Union before the assembly of the League of Nations , precursor of the United Nations. Seven countries have since joined. In , after the fall of the Eastern Bloc , the former East Germany became part of the Communities as part of a reunified Germany. The euro currency became the second largest reserve currency in the world. In , Bulgaria and Romania became EU members. Treaty of Rome —92 The continental territories of the member states of the European Union European Communities pre , coloured in order of accession. Attempts to solve the problems and to make the EU more efficient and coherent had limited success.