Which of the following ancient peoples was NOT classified as Hellenic (Greek)?

The story behind the answer

Illyrians is correct because they were a distinct Indo-European people of the western Balkans, with their own languages and cultures, not part of the Hellenic (Greek) ethnos. By contrast, Ionians, Achaeans, and Dorians are all major Greek groups: Ionians in Attica and Asia Minor, Achaeans often associated with the Mycenaean Greeks of Homer, and Dorians linked to Sparta and much of the Peloponnese—each with characteristic Greek dialects and traditions.

Context tip: Classical Greeks often divided themselves into Ionian, Dorian, and Aeolian/Achaean branches. The Illyrians were their neighbors and sometime rivals; later Rome organized the region as Illyricum. Memory hook: “DIA are Greek—Dorians, Ionians, Achaeans; Illyrians live outside the ‘DIA’ of Hellas.”