Hence, the vast majority of Thrace remained unaffected by the Persian presence. After the failed invasion of Greece in 480-79, the Persian foothold in Europe collapsed. By around 450, Persian authority in Europe, including Thrace, had vanished entirely. Foundation and early years ( 480–431 BC) Early tribal kingdom Although the Persian presence in Thrace was short-lived, it probably stimulated trade and first state formations among the Thracians. Mintings of Thracian coins started around 500 and may be an indicator for a variety of early tribal kingdoms. It has been suggested that the Odrysian kingdom might have had its origins in this period, even though the name of the Odrysians is notably absent from the numismatic evidence. The Odrysians eventually stepped into the light of history in the aftermath of the Persian failure in Greece, when they were mentioned by Herodotus, but without any further details. The Odrysians had their core territory in the valleys of the Hebros river and its tributaries Tonzos and Arda. Like other Thracian polities, the Odrysian tribal kingdom attempted to fill the vacuum left by the Persian retreat. Expansion under Teres I The first known Odrysian king was the expansionist Teres I, who is claimed by Thucydides to have been the first Odrysian king altogether. Writing in the late 5th century BC, he wrote that Teres "was the first powerful king of the Odrysae" and that he "was the first founder of the great Odrysian empire, which he extended over a large part of Thrace, although many of the Thracian tribes are still independent." Said independent tribes consisted of Thracians living along parts of the Aegean coast and in parts of the Rhodope mountains and as well as the powerful Triballi around the Haemus. Teres most likely came to dominate central Thrace soon after 480 BC. Building his realm on a privileged warrior aristocracy, he and his son Sitalces expanded the realm from the Danube in the north to the outskirts of Abdera at the Aegean Sea. He also expanded to eastern Thrace, although he suffered a setback at the hands of the Thynoi. In the north-east, he cemented the position of his realm by allying himself with the kingdom of Scythia under king Ariapeithes, who married Teres' daughter. In conclusion, the Odrysians were the first to supersede the Thracian tribal system and establish a large state in the eastern Balkans. Around the middle of the