Panhellenism
/panˈhɛlɪnɪz(ə)m/noun
Panhellenic spirit or ideals; specifically (in ancient times) patriotism based on the idea of Greek culture as a whole rather than individual cities and states; (in the 19th and early 20th centuries) advocacy of a political union of all Greek-speaking peoples, Greek irredentism.
Origin
Mid 19th century; earliest use found in The Times. From ancient Greek Πανέλληνες + -ism, after Panhellenic.