Which country's ancient name was Hellas?

Greece, which still calls itself Hellas - Ellada - and has never called itself Greece. The English name comes through Latin Graecia, apparently from a small tribe the Romans encountered early and generalised, so an entire civilisation is known internationally by the name of a group most Greeks would not have recognised.

This is a common pattern and Greece is the clearest case. Germany calls itself Deutschland and is Allemagne to the French and Niemcy to the Poles; Finland is Suomi; Japan is Nihon; Egypt is Misr; India is also Bharat. Endonyms and exonyms diverge because names were usually applied by neighbours rather than chosen.

It became a live political question in 2018 over the country to the north. Greece objected for nearly thirty years to the name Macedonia, on the grounds that it belonged to a Greek historical region and implied a claim on it, blocking that country's EU and NATO accession. The Prespa Agreement settled it as North Macedonia, and the naming argument - which most outsiders found baffling - was serious enough to occupy two governments for a generation.