Question

Линия разделяющая материковую грецию на три части

Answer 1

Македония — северная область Греции, граничащая с Албанией, Болгарией и бывшей Югославией; 
Фракия — северо–восточная область, граничащая с Болгарией и Турцией; 
Эпир — северо–западная область, граничащая с Албанией, с юго–запада омывается Ионическим морем;

Answer 2

The Division of Mainland Greece

The mainland of Greece is divided into three parts. The line that separates these parts is known as the "Gulf of Corinth".

The Gulf of Corinth separates the Peloponnese from the Greek mainland. It is a deep inlet of the Ionian Sea that cuts through the narrow Isthmus of Corinth.

This information is supported by various sources: - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth" - Source "Gulf of Corinth"