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Schengen and the European Convention

About Schengen The Schengen States are a group of European countries that have abolished border controls. The Schengen countries have reached agreements with each other on visa policy, asylum 
policy and cooperation between police and judicial authorities.
The Schengen accord allows for the movement of 26 countries, most of them members of the European Union, but some countries have re-controlled their borders because of the refugee crisis and the threat of terrorism
The Schengen region has a population of more than 400 million, an area of ​​about 431,299 square kilometers (166,491 square miles).
The first members were Belgium, France, Germany, Luxembourg and the Netherlands. Now there are 26 Schengen states - 22 EU members and four non-EU members. These four are

Iceland, Norway (since 2001), Switzerland (since 2008) and Liechtenstein (since 2011).
The first five were in Italy (1990), Portugal, Spain (1991), Greece (1992), Austria (1995), Denmark, Finland and Sweden in 1996.
Nine EU countries joined in 2007, following the EU's eastward expansion in 2004. The Czech Republic, Estonia, Hungary, Lithuania, Latvia, Malta, Poland, Slovakia and Slovenia.
Only six of the 28 member states of the European Union are outside the Schengen-Bulgaria, Croatia, Cyprus, Ireland, Romania and the United Kingdom.
As a result of the continuing immigration crisis and the terrorist attacks in Paris, some countries restored some or all of their borders with the Schengen countries on 22 March 2016 between Austria, Belgium, Denmark, France, Germany, Norway and Sweden who imposed one or both Border with the Schengen States.

The Schengen Agreement
The member States of the European Common Market (EEC) failed to reach a decision satisfactory to all parties regarding the demarcation of their borders. This led to the signing of the Schengen Agreement, signed for the first time on 14 January 1986 by five EU member states. The Convention was developed so that its features appeared clear. It emerged from the European Union's shell and

laid down its basic principles of the abolition of the border and common visa, which was later known as the Schengen visa. The appearance of the Schengen area was officially established on 26 March 1995. Over time, more countries entered the European Union in the Schengen area, drawing the attention of the Union to the need for the Schengen Convention to be put into effect. In 1997, the Treaty of Amsterdam was signed by which the Schengen Convention was incorporated into the European Union law, Since 1999, as a result of the European Union's control of the Convention, the enactment of all Schengen Agreement laws and legislation has been restricted to EU countries only. Ireland and the United Kingdom have refused to abolish controls on their borders and have thus been subjected to a full withdrawal from the Convention.