The first mention of Dion in history comes from Thucydides, who reports that it was the first city reached by the Spartan general Brasidas after crossing from Thessaly into Macedon on his way through the realm of his ally Perdiccas II during his expedition against the Athenian colonies of Thrace in 424 BC. According to Diodorus Siculus, it was Archelaus I who, at the end of the 5th century BC when the Macedonian state acquired great power and emerged onto the stage of history, gave the city and its sanctuary their subsequent importance by instituting a nine-day festival of games that included athletic and dramatic competitions in honor of Zeus and the Muses, whose organisation was overseen by the Macedonian kings themselves.