The Proto-Ionians are the hypothetical earliest speakers of the Ionic dialects of Ancient Greek, chiefly in the works of Jean Faucounau. The relation of Ionic to the other Greek dialects has been subject to some debate. It is mostly grouped with Arcadocypriot as opposed to Doric, reflecting two waves of migration into Greece following the Proto-Greek period, but sometimes also as separate from Arcadocypriot on equal footing with Doric, suggesting three distinct waves of migration.
Mainstream Greek linguistics separates the Greek dialects into two large genetic groups, one including Doric Greek and the other including both Arcadocypriot and Ionic Greek. But alternative approaches proposing three groups are not uncommon; Thumb and Kieckers (1932) propose three groups, classifying Ionic as genetically just as separate from Arcadocypriot as from Doric. Like a few other linguists (Vladimir Georgiev, C. Rhuijgh, P. Léveque, etc.), The bipartite classification is known as the "Risch–Chadwick theory", named after its two famous proponents, Ernst Risch and John Chadwick.
The "Proto-Ionians" first appear in the work of Ernst Curtius (1887), who believed that the Attic-Ionic dialect group was due to an "Ionicization" of Attica by immigration from Ionia in historical times. Curtius hypothesized that there had been a "Proto-Ionian" migration from the Balkans to western Anatolia in the same period that brought the Arcadic dialect (the successor of the Mycenean Greek stage yet undiscovered in the time of Curtius) to mainland Greece. Curtius' hypothesis was endorsed by George Hempl in 1920. Hempl preferred to call these hypothetical, early Anatolian Greeks "Javonians". Hempl attempted to defend a reading of Hittite cuneiform as Greek, in spite of the establishment of the Hittite language as a separate branch of Indo-European by Hrozný in 1917.