The probable origin of the story is the part traditionally taken in the foundation of Syracuse by the Iamidae of Olympia, who identified the spring Arethusa with their own river Alpheus, and the nymph with Artemis Alpheiaia, who was worshipped at Ortygia.
The subterranean passage of the Alpheus in the upper part of its course (confirmed by modern explorers), and the freshness of the water of Arethusa in spite of its proximity to the sea, led to the belief that it was the outlet of the river.
Alpheus was recognized in cult and myth as the chief or typical river-god in the Peloponnesus, as was Achelous in northern Greece.
His waters were said to pass beneath the sea and rise again in the fountain Arethusa at Syracuse; such is the earlier version from which later mythologists and poets evolved the familiar myth of the loves of Alpheus and Arethusa.
By its vicinity to the watersheds of the Eurotas and Alpheus, and its command over the main roads from Laconia to Argos and the Isthmus, Tegea likewise was brought into conflict with Sparta.