Greco-Bactrian Kings

The Bactrian Kingdom, known to historians as the Greco-Bactrian Kingdom or simply Greco-Bactria, was a Hellenistic-era Greek state, and along with the Indo-Greek Kingdom, the easternmost part of the Hellenistic world in Central Asia and the Indian Subcontinent from its founding in 256 BC by Diodotus I Soter to its fall BC under the reign of Heliocles I. It covered much of present-day Afghanistan, Uzbekistan, Tajikistan and Turkmenistan, and at its zenith, parts of Iran and Pakistan. An extension further east with military campaigns may have reached central Gansu province in China. Bactria was ruled by the Diodotid dynasty and rival Euthydemid dynasty. The capitals of Ai-Khanum and Bactra were among the largest and richest of antiquity - Bactria itself was known as the ‘''land of a thousand golden cities’''. The Indo-Greek Kingdoms, as Bactrian successor states, would last until 10 AD.

History

Independence and Diodotid dynasty

Diodotus, the satrap of Bactria (and probably the surrounding provinces) founded the Greco-Bactrian Kingdom when he seceded from the Seleucid Empire around 250 BC and became King Diodotus I of Bactria. The preserved ancient sources (see below) are somewhat contradictory, and the exact date of Bactrian independence has not been settled. Somewhat simplified, there is a high chronology ( BC) and a low chronology (c. 246 BC) for Diodotos' secession. The high chronology has the advantage of explaining why the Seleucid king Antiochus II issued very few coins in Bactria, as Diodotos would have become independent there early in Antiochus' reign. On the other hand, the low chronology, from the mid-240s BC, has the advantage of connecting the secession of Diodotus I with the Third Syrian War, a catastrophic conflict for the Seleucid Empire.
), defected and proclaimed himself king; all the other people of the Orient followed his example and seceded from the Macedonians.

The new kingdom, highly urbanized and considered one of the richest of the Orient (''opulentissimum illud mille urbium Bactrianum imperium'' "The extremely prosperous Bactrian empire of the thousand cities"), was to further grow in power and engage in territorial expansion to the east and the west:

In 247 BC, the Ptolemaic empire (the Greek rulers of Egypt following the death of Alexander the Great) captured the Seleucid capital, Antioch. In the resulting power vacuum, Andragoras, the Seleucid satrap of Parthia, proclaimed independence from the Seleucids, declaring himself king. A decade later, he was defeated and killed by Arsaces of Parthia, leading to the rise of a Parthian Empire. This cut Bactria off from contact with the Greek world. Overland trade continued at a reduced rate, while sea trade between Greek Egypt and Bactria developed.

Diodotus was succeeded by his son Diodotus II, who allied himself with the Parthian Arsaces in his fight against Seleucus II:

Euthydemid dynasty and Seleucid invasion

Euthydemus, a Greek from Magnesia according to Polybius, and possibly satrap of Sogdiana, overthrew the dynasty of Diodotus II around 230–220 BC and started his own dynasty. Euthydemus's control extended to Sogdiana, going beyond the city of Alexandria Eschate founded by Alexander the Great in Ferghana:

And they also held Sogdiana, situated above Bactriana towards the east between the Oxus River, which forms the boundary between the Bactrians and the Sogdians, and the Iaxartes River. And the Iaxartes forms also the boundary between the Sogdians and the nomads.

Euthydemus was attacked by the Seleucid ruler Antiochus III around 210 BC. Although he commanded 10,000 horsemen, Euthydemus initially lost a battle on the Arius and had to retreat. He then successfully resisted a three-year siege in the fortified city of Bactra (modern Balkh), before Antiochus finally decided to recognize the new ruler, and to offer one of his daughters to Euthydemus's son Demetrius around 206 BC. Classical accounts also relate that Euthydemus negotiated peace with Antiochus III by suggesting that he deserved credit for overthrowing the original rebel Diodotus and that he was protecting Central Asia from nomadic invasions thanks to his defensive efforts:

In an inscription found in the Kuliab area of Tajikistan, in eastern Greco-Bactria, and dated to 200–195 BC,Shane Wallac
Greek Culture in Afghanistan and India: Old Evidence and New Discoveries
p.206 a Greek by the name of Heliodotos, dedicating a fire altar to Hestia, mentions Euthydemus as the greatest of all kings, and his son Demetrius I as "Demetrios Kalinikos" "Demetrius the Glorious Conqueror":

Following the departure of the Seleucid army, the Bactrian kingdom seems to have expanded. In the west, areas in north-eastern Iran may have been absorbed, possibly as far as into Parthia, whose ruler had been defeated by Antiochus the Great. These territories possibly are identical with the Bactrian satrapies of Tapuria and Traxiane.

Expansion into the Indian subcontinent (after 180 BC)

Demetrius, the son of Euthydemus, started an invasion of the subcontinent from 180 BC, a few years after the Mauryan empire had been overthrown by the Shunga dynasty. Historians differ on the motivations behind the invasion. Some historians suggest that the invasion of the subcontinent was intended to show their support for the Mauryan empire, and to protect the Buddhist faith from the religious persecutions of the Shungas as alleged by Buddhist scriptures (Tarn). Other historians have argued however that the accounts of these persecutions have been exaggerated ( Thapar, Lamotte).

Demetrius may have been as far as the imperial capital Pataliputra in today's eastern India (today Patna). However, these campaigns are typically attributed to Menander. The invasion was completed by 175 BC. This established in the northwestern Indian Subcontinent what is called the Indo-Greek Kingdom, which lasted for almost two centuries until around 10 AD. The Buddhist faith flourished under the Indo-Greek kings, foremost among them Menander I.
It was also a period of great cultural syncretism, exemplified by the development of Greco-Buddhism.

Eucratides

Back in Bactria, Eucratides, either a general of Demetrius or an ally of the Seleucids, managed to overthrow the Euthydemid dynasty and establish his own rule around 170 BC, probably dethroning Antimachus I and Antimachus II. The Indian branch of the Euthydemids tried to strike back. An Indian king called Demetrius (very likely Demetrius II) is said to have returned to Bactria with 60,000 men to oust the usurper, but he apparently was defeated and killed in the encounter:

Eucratides led many wars with great courage, and, while weakened by them, was put under siege by Demetrius, king of the Indians. He made numerous sorties, and managed to vanquish 60,000 enemies with 300 soldiers, and thus liberated after four months, he put India under his rule.

Eucratides campaigned extensively in present-day northwestern India, and ruled a vast territory, as indicated by his minting of coins in many Indian mints, possibly as far as the Jhelum River in Punjab. In the end, however, he was repulsed by the Indo-Greek king Menander I, who managed to create a huge unified territory.

In a rather confused account, Justin explains that Eucratides was killed on the field by "his son and joint king", who would be his own son, either Eucratides II or Heliocles I (although there are speculations that it could have been his enemy's son Demetrius II). The son drove over Eucratides' bloodied body with his chariot and left him dismembered without a sepulchre:

As Eucratides returned from India, he was killed on the way back by his son, whom he had associated to his rule, and who, without hiding his parricide, as if he didn't kill a father but an enemy, ran with his chariot over the blood of his father, and ordered the corpse to be left without a sepulture.

Defeats by Parthia

During or after his Indian campaigns, Eucratides was attacked and defeated by the Parthian king Mithridates I, possibly in alliance with partisans of the Euthydemids:

The Bactrians, involved in various wars, lost not only their rule but also their freedom, as, exhausted by their wars against the Sogdians, the Arachotes, the Dranges, the Arians and the Indians, they were finally crushed, as if drawn of all their blood, by an enemy weaker than them, the Parthians.

Following his victory, Mithridates I gained Bactria's territory west of the Arius, the regions of Tapuria and Traxiane: "The satrapy Turiva and that of Aspionus were taken away from Eucratides by the Parthians."

In the year 141 BC, the Greco-Bactrians seem to have entered in an alliance with the Seleucid king Demetrius II to fight again against Parthia:

The people of the Orient welcomed his (Demetrius II's) arrival, partly because of the cruelty of the Arsacid king of the Parthians, partly because, used to the rule of the Macedonians, they disliked the arrogance of this new people. Thus, Demetrius, supported by the Persians, Elymes and Bactrians, routed the Parthians in numerous battles. At the end, deceived by a false peace treaty, he was taken prisoner.

The 5th century historian Orosius reports that Mithridates I managed to occupy territory between the Indus and the Hydaspes towards the end of his reign ( BC, before his kingdom was weakened by his death in 136 BC).

Heliocles I ended up ruling what territory remained. The defeat, both in the west and the east, may have left Bactria very weakened and open to nomadic invasions.

Nomadic invasions

A nomadic steppe people called the Yuezhi inhabited a region thousands of miles to the east of Bactria on the edges of the Han Empire called the Hexi Corridor. Shortly before 176 BC, the Xiongnu invaded the Hexi Corridor, forcing the Yuezhi to flee the region. In 162 BC the Yuezhi were driven west to the Ili River valley by the Xiongnu. In 132 they were driven out of the Ili valley by the Wusun