From around 450BC the sphere of Greek influence began to shift away from the Hellenic mainland towards the East and their opponents there required a shift in Hoplite tactics. Many of their enemies lived in areas where there was much broken ground, woods, mountains etc so the increase in skirmishing troops numbers and quality was noticeable. This was also the time of the great mercenary companies who performed incredible feats of martial skill and personal endurance as they fought for control of Empires and Kingdoms.
Although the armies described above remained based upon the Hoplite the percentage of supporting troops increased from around 10% to 15%. This was mainly due to a developing cavalry arm, several states recruited more citizen cavalry. Athens even experimented with mounted archers for a time. Thracian tribal foot were employed as mercenaries to augment the numbers of Peltasts, Sparta and Athens also hired Thracian cavalry. After 400BC Peltasts began to use the heavier defensive and offensive equipment noted above and take more of a part in the main battle. The use of mixed cavalry and javelin skirmishers became more widespread especially by Athens, Thebes, Thessaly and Sparta.
(Excerpt from text on the World of the Greeks page by Adrian Garbett)
Our Thracians were sculpted by Steve Saleh and Nick Collier with Mark Copplestone.