The historical boundaries of Thrace have varied. Ancient Thrace (i.e. the territory where ethnic Thracians lived) included present day Bulgaria, European Turkey, north-eastern Greece and parts of eastern Serbia and eastern Republic of Macedonia. Its boundaries were between the Danube River to the north and the Aegean Sea to the south, to the east - the Black Sea and the Sea of Marmara and on the west to the Vardar and Great Morava rivers. The Roman province of Thrace was somewhat smaller, having the same eastern maritime limits and being bounded on the north by the Balkan Mountains; the Roman province extended west only to the Mesta River.
These Indo-European peoples, while considered barbarian and rural by their refined and urbanized Greek neighbors, had developed advanced forms of music, poetry, industry, and artistic crafts. Aligning themselves in petty kingdoms and tribes, they never achieved any form of national unity beyond short, dynastic rules at the height of the Greek classical period. Similar to the Gauls and other Celtic tribes, most people are thought to have lived simply in small fortified villages, usually on hilltops. Although the concept of an urban center wasn't developed until the Roman period, various larger fortifications which also served as regional market centers were numerous. Yet, in general, despite Greek colonization in such areas as Byzantium, Apollonia or Tomi, the Thracians avoided urban life.
The Thracians fell early under the cultural influence of the ancient Greeks, preserving until a much later time, however, their language and culture. It also appears from mythological accounts that the Thracians influenced Greek culture from a very early period, with some Thracians, such as Orpheus, even appearing as culture-bearers in some myths. But as non-Greek speakers, they were viewed by the Greeks as barbarians. The first Greek colonies in Thrace were founded in the 6th century BC.
Throughout the 6th century BC, Thracian infantry was heavily recruited by Greek states and large deposits of gold and silver were mined.
Thrace south of the Danube (except for the land of the Bessi) was ruled for nearly half a century by the Persians under Darius the Great, who conducted an expedition into the region from 513 BC to 512 BC.
Before the expansion of the kingdom of Macedon, Thrace was divided into three camps (East, Central, and West) after the withdrawal of the Persians. A notable ruler of the East Thracians was the overking Cersobleptes, who attempted to expand his power over many of the Thracian tribes. He was eventually defeated by the Macedonians.
The region was conquered by Philip II of Macedon in the 4th century BC and was ruled by the kingdom of Macedon for a century and a half. During the Macedonian Wars, conflict between Rome and Thracia was inevitable. The destruction of the ruling parties in Macedonia destabilized their authority over Thrace, and its tribal authorities began to act once more on their own accord. After the battle of Pydna in 168 BC, Roman authority over Macedonia seemed inevitable, and the governing of Thracia passed to Rome. Neither the Thracians nor the Macedonians had yet resolved themselves to Roman dominion, and several revolts took place during this period of transition. The revolt of Andriscus in 149 BC, as an example, drew the bulk of its support from Thracia. Several incursions by local tribes into Macedonia continued for many years, though there were tribes who willingly allied themselves to Rome, such as the Deneletae and the Bessi.
The next century and a half saw the slow development of Thracia into a permanent Roman client state. The Sapaei tribe came to the forefront initially under the rule of Rhascuporis. He was known to have granted assistance to both Pompey and Caesar, and later supported the Republican armies against Antonius and Octavian in the final days of the Republic. The familiar heirs of Rhascuporis were then as deeply tied into political scandal and murder as were their Roman masters. A series of royal assassinations altered the ruling landscape for several years in the early Roman imperial period. Various factions took control, with the support of the Roman Emperor. The turmoil would eventually stop with one final assassination.
In 279 BC, Celtic Gauls advanced into Macedonia, Southern Greece and Thrace. They were soon forced out of Macedonia and Southern Greece, but they remained in Thrace until the end of the century. From Thrace, three Celtic tribes advanced into Anatolia and formed a new kingdom called Galatia.
After Roimitalkes III of the Thracian Kingdom of Sapes was murdered in 46 by his wife, Thracia was incorporated as an official Roman province to be governed by Procurators, and later Praetorian Prefects. The central governing authority of Rome was based in Perinthus, but regions within the province were uniquely under the command of military subordinates to the governor. The lack of large urban centers made Thracia a difficult place to manage, but eventually the province flourished under Roman rule. However, Romanization was not attempted in the province of Thracia. It is considered that most of the Thracians were Hellenized in these times.
Roman authority of Thracia rested mainly with the legions stationed in Moesia. The rural nature of Thracia's populations, and distance from Roman authority, certainly inspired the presence of local troops to support Moesia's legions. Over the next few centuries, the province was periodically and increasingly attacked by migrating Germanic tribes. The reign of Justinian saw the construction of over 100 legionary fortresses to supplement the defense.
Owing to their martial reputation, the Thracian tribesmen were much used as mercenaries by the Greek kings of Syria, Pergamum, Bithynia, and other regions. Thracian mercenaries were always in demand, as they were fierce fighters, especially in rocky or hilly regions similar to their homeland. They were however considered a bit expensive at times, and liable to switch sides. The principal Thracian weapons in the fifth and fourth centuries were the spear and the knife. Much earlier Thracian infantry had been armed with axes, while their leaders rode chariots. Thracian light infantry could be armed with javelins, slings, or bows, with javelins predominating. Thracian warriors, particularly the hillmen, were especially famous for an unusual weapon which combined elements of sword, sickle and polearm, which was called the Rhomphaia, and was carried increasingly by Thracian infantry in the centuries following Alexander the Great's death until it became a trademark of the mercenary Thracian peltast. Even the Romans dreaded this fearsome weapon. Cavalry armament for all Thracians except the Getae consisted of 2 cornel wood javelins that could be thrust with or thrown. They also carried the typical Kopis. The Getae often used bows instead of javelins, and the akinakes instead of the kopis. Thracian tribes also used more exotic weapons such as spiked axles, or carts rolled down steep hills. Thracians were known for their hit and run tactics consisting of random melee attacks followed by quick retreats. The backbone of the Thracian military were the Thracian Peltast, a type of light infantry that was equally at home fighting hand-to-hand and at a distance (throwing javelins). Peltasts were unarmored except for their curved shields. They carried some form of short sword or melee weapon and an assortment of javelins. The wealthy nobility wore helmets with pointed tops in order to accommodate their top-knot hairstyles.
The Thracian calendar was similar to that of the Egyptians. Each year had twelve months, totaling 360 days, and 5 days were added to the last month; there were three seasons. The Thracians celebrated 60 main holidays.
In 1878, Northern Thrace was incorporated into the semi-autonomous Ottoman province of Eastern Rumelia, which united with Bulgaria in 1885. The rest of Thrace was divided between Bulgaria, Greece and Turkey at the beginning of the 20th century, following the Balkan Wars, World War I and the Greco-Turkish War. Today Thracian is a strong regional identity in Greece, Bulgaria and Turkey.