What is "hilleviones"

The Hilleviones were a Germanic people occupying an island called Scatinavia in the 1st century AD, according to the Roman geographer Pliny the Elder in Naturalis Historia (Book 4, Chapter 96), written circa 77 AD. Pliny's Scatinavia is generally believed to have referred to the Scandinavian peninsula, which in the 1st century AD had not yet been fully explored by the Romans and was therefore described as an island. Pliny wrote that it was an island "of a magnitude as yet unascertained". The Hilleviones lived in the only part of the island that was known, and according to Pliny, they thought of their 500 villages as a separate (alterum) world.