His genealogy was traced through Aristodemus, Aristomachus, Cleodaeus and Hyllus to Heracles (Herodotus vii.
Services rendered to Aegimius by Heracles led (I) to the adoption of Hyllus, son of Heracles, by Aegimius, side by side with his own sons Dymas and Pamphylus, and to a threefold grouping of the Dorian clans, as Hylleis, Dymanes and Pamphyli; (2) to the association of the people of Aegimius in the repeated attempts of Hyllus and his family to recover their lost inheritance in VIII.
In the 5th century Pindar ascribes to Aegimius the institutions of the Peloponnesian Dorians, and describes them as the " Dorian folk of Hyllus and Aegimius," and as " originating from Pindus " (Pyth.
From Trachis he wages successful war against the Dryopes and Lapithae as ally of Aegimius, king of the Dorians, who promised him a third of his realm, and after his death adopted Hyllus, his son by Deianeira.
HERACLIDAE, the general name for the numerous descendants of Heracles (Hercules), and specially applied in a narrower sense to the descendants of Hyllus, the eldest of his four sons by Deianeirathe, conquerors of Peloponnesus.