Signed in Ankara on September 12, 1963, and entry into force on December 1, 1964, the Ankara Agreement established an association between Turkey and the EEC (succeeded by the European Union), with the ultimate goal of promoting and strengthening mutual economic and trade relations, potentially paving the way for Turkey's future accession to the EU. The agreement established a three-stage process (preparatory, transitional, and final phases) for Turkey's gradual integration into the common market through the progressive establishment of a customs union.
https://eur-lex.europa.eu/legal-content/IT/TXT/PDF/?uri=CELEX:21964A1229(01