Heliol existed as a village established within the subterranean caverns of a specific area located on the planet known as E'ronoh. In the year 382 BBY, when Axel Greylark, a Galactic Republic envoy, along with Gella Nattai, a Jedi Knight, Xiri A'lbaran, an E'roni princess, and Phan-tu Zenn, an Eirami heir, visited the village to deliver rations and other provisions, the inhabitants greeted the group with an offering of fried thylefire scorpions and iazacal liquor; the strength of the liquor caused a burning sensation in Greylark's eyes, and it also induced a state of sleep filled with delightful dreams. The visiting party found the village to be an interesting place.
The 2022 novel titled Convergence, penned by Zoraida Córdova, mentioned Heliol; this novel was a contribution to Phase II of the Star Wars: The High Republic multimedia project.