In 1968, and in response to their interpretation of events in Czechoslovakia as a "Soviet invasion" during the party conference that took place in Budapest (KKE was banned in Greece and many of its members lived in exile), a number of the members of KKE expressed their disagreement with the party majority and left the party. They were joined by a number of party members living in Greece, and continuing party activity in a clandestine manner.
Those who left KKE called their party "KKE of the Interior" (ΚΚΕ Εσωτερικού), suggesting that everyone who had stayed loyal to KKE was a member of a "KKE of the exterior", that is to say, a Soviet Union operative rather than a true Greek. To emphasize their point, their party emblem featured the Greek flag behind the hammer and sickle which was the emblem of the KKE.
Nicos Poulantzas, then living in Paris, France, became the most important intellectual voice of the "KKE of the Interior", whose orientation was, however paradoxically for a party that pointed at others as "suspiciously internationalist", Eurocommunist, and in line with Italian and Spanish Eurocommunism. Of course, the "internationalism" the KKE "of the Interior" rejected was socialist internationalism; the internationalism it upheld was the "internationalism" of the west European left.
In in its 4th conference, in 1986, the members of "KKE of the Interior" decided to transform it into a non-communist party and the party splinter split in turn. Those who followed the majority line renamed the party "Greek Left" (Ελληνική Αριστερά). Α minority faction, which argued for an "upgrading" of the KKE of the Interior formed "KKE of the Interior - Left Revival", later to be named AKOA, which subsequently became one of the constituents of SYRIZA.
In 1992, after the KKE left the electoral alliance Coalition of the Left and of Progress, in which it had collaborated with the "Greek Left" in the Tzannetakis government (an event precipitated by a new split within the KKE, when, in 1991, a big number of its remaining members --including 39 CC members and 5 MPs-- defected to the "Greek Left" or formed smaller splinter groups), the "Greek Left" renamed itself "Coalition of the Left and of Progress", or Synaspismos (SYN).
In 2004, SYN was joined by a number of the splinter groups generated by the first and second split within the KKE, as well as by other, independent groups, to form SYRIZA.