Fostering the free movement of people has been an important objective of European integration since the 1950s. Free movement of goods, persons, services and capital were identified as foundations of the Community in the Treaty of Rome (1957).
Schengen.
During the 1980s five Member States (Belgium, France, Germany, Luxembourg, the Netherlands) decided to create a territory without internal borders. They signed the first agreements in a small town in Luxembourg called Schengen hence, the "Schengen area" -- a territory in which the free movement of persons is guaranteed. The original agreement was complemented in 1990 by a convention.
When this convention entered into force in 1995 it abolished checks at the internal borders and created a single external border. Whatever their location is officers working at the external border perform border checks in accordance with identical procedures. The rules governing visas and the right to asylum are also common for all Schengen countries.
In order to keep the balance between freedom and security, participating member states agreed to introduce so-called "compensatory measures". These are focused on cooperation and coordination of the work of the police and judicial authorities. Organised crime networks do not respect borders; therefore this cooperation is key to safeguarding internal security.
In 1999 with the signing of the Treaty of Amsterdam this intergovernmental cooperation was incorporated into the EU framework.
On the 26 October 2004 the European Agency for the Management of Operational Cooperation at the External Borders of the Member States of the European Union (Frontex) was established by Council Regulation (EC) 2007/2004.