During the first half of the 6th century, BCE Babylonian King Nebuchadnezzar ruled Harran. The town was home to the Sabian worshippers of the moon god Sin. The mystical Sabian sect was, because of its belief in one God, recognised by Islam as on a par with Christianity and Judaism. The Sabian religion united Neo-Platonic philosophy with Babylonian astrology, considering the planets as embodying spiritual beings created by God as part of the universe, especially the moon, whose god they called Sin. The Sabians had a holy script, ceremony and a kind of communion. Facing always to the north, they prayed at dawn, midday and sunset. The principal deity was worshipped in the form of a pillar or holy stone, and under him were the sun god (Shamash), the moon god (Sin), Saturn (Kronos), Jupiter (Bel), Mars (Ares), Venus (Balti), and Mercury (Nabuq). Every day of the week was dedicated to one of these deities.

The main moon god sanctuary was at Harran where the cult was practised into the 12th century. In 830 CE, the caliph Al-Mamun was filled with indignation at the dress, long hair and scandalous behaviour of the Sabians and gave them the choice of converting to Islam or Christianity or face exile or hanging. One medieval Arab chronicler wrote of their wild practices: "There was no hill that was not moist with the blood of sacrifices and no high place that was empty of libations. Youths in multitudes were given as sacrifices, and maidens slaughtered to female idols and to the sun and the moon and Venus and other luminaries".

The original moon temple at Harran was one of the holiest sanctuaries of the Middle East, and the Harran astronomers were held in high regard by the brilliant court of the Abbasids in Baghdad in the 9th century. Their religious emblem of a crescent and an eight-pointed star was subsequently adopted by a variety of esoteric sects and the spread of the crescent and star symbol, still so prevalent in the Islamic world, seems to date from that time.

According to the Old Testament, Harran was also the place where Terah and his son Abraham, his grandson Lot and Abraham’s wife Sarah went after leaving Ur. It was 18 centuries before Christ that Abraham was called from Ur of the Chaldees to go to Canaan according to the Old Testament. He stopped at Harran for several years until God told him to move on:

"So Abram departed, as the Lord had spoken unto him: and Abram was seventy and five years old when he departed out of Harran. And Abram took Sarai his wife and Lot his brother’s son and all their substance that they had gathered, and the souls that they had gotten in Harran; and they went forth to go into the land of Canaan (Genesis 12:4-5)."

Although Abraham went on to Canaan after his father Terah died, some relatives apparently remained. Much later Abraham sent a servant back to Harran to find a wife from among his relatives for his son Isaac. The traditional site of Jacob's Well, where Rebecca drew water for Abraham's servant is about one km west of the Harran city walls. According to tradition, Harran was where Jacob laboured for twenty years for his father-in-law Laban. Travellers keen on walking and at the same time supporting the local economy can follow the so-called "Abraham's Path" that begins in Turkey, runs for 170 km through flattish semi-arid landscapes and incorporates the major sights of Urfa, Göbekli Tepe, the Well of Job, Harran, the Well of Jacob and Sogmatar.

Harran was also part of the Achaemenid Empire, which was replaced two centuries later by that of the Macedonian king Alexander the Great. The conqueror may have visited Harran in the late summer of 331 BCE. After Alexander's death in 323 BCE, Harran was part of the empire of the Seleucids, the Macedonian dynasty ruling in Asia. They settled Macedonian veterans at Harran, which remained a recognisable entity after the Seleucid empire had been replaced by that of the Parthians.

In 53 BCE, the Roman general Crassus invaded Parthia. The descendants of the Macedonians sided with him, but he was defeated by a Parthian commander, called Surena in the Greek and Latin sources, who must have been a member of the Parthian Sûrên clan. The battle of Harran - or Carrhae as the Romans called it - was the beginning of a series of border wars that were to last for centuries.

The battle of Carrhae

In the year 53 BC, on the plain east of Harran in ancient Mesopotamia, the battle of Carrhae took place. At that battle, the Roman general Marcus Crassus, one of the triumvirs, was defeated by the Parthian general Surena, who fought there by order of king Orodes II. Surena had prepared particularly well for the battle by entering into an alliance with King Artavasdes II of Armenia.

The Greek author Ploutarchos presents the area as a dry desert full of sand dunes in which the Roman legionaries could not get on well. That landscape is still mentioned in many publications as the explanation for the Roman defeat. And it has to be said: the current road towards Şanliurfa, just north of Harran, indeed runs through a desolate and arid area.

In reality, however, Harran lies on the Balikh river, something that Ploutarchos, unlike his contemporary followers, does mention. Not far downstream on Syrian territory lies the Tell Sabi Abbyad, investigated by Dutch archaeologists, from where in Assyrian times the agricultural exploitation of the river valley was led.

It would be an exaggeration to count the Harran area among the most fertile areas of the Near East, but desert sand was not the cause of the Roman defeat. The real reason is the Parthian heavy cavalry and the ability of the Parthian archers to shoot hundreds of thousands of arrows. Underestimation of the military capabilities of the old-eastern armies is the reason why ancient historians let Crassus' men march into a non-existent desert.

A partial description of the events can be found in "The History of Rome since its foundation" by the Roman historian Livius who states the following: "Marcus Crassus crossed the Euphrates, brought the war to the Parthian Empire and was defeated in a battle in which he as well as his son died. With the remains of his army, he occupied a hill and was invited by the enemy leader Surena to a meeting to negotiate a truce. However, Crassus was captured and killed to spare him the humiliation of staying alive after the defeat".

The story of the battle itself is depicted in detail by Ploutarchos in his "Life of Crassus". The battle itself took place near the river, probably south of the city of Carrhae (Harran). After the defeat, the Romans went to Harran. During the night, they left the place and lost their way in the numerous swamps which forced them to negotiate with the enemy, losing their general, as mentioned above.

The main reason for the Parthian victory had nothing to do with betrayal or with a desert in which the Romans could not deploy their army. These fallacies were simply invented to hide the fact that the Parthians were superior to the Romans in quality and number of men. The Parthians had better supply lines where caravans of dromedaries brought them thousands of arrows to bombard the Romans with. That was the real cause of the Roman defeat.

The death of Crassus meant at the same time that only Pompey the Great and Julius Caesar remained of the once-mighty Roman triumvirate. As there was nothing left to maintain the balance between the two, sooner or later, the two men were led towards a civil war.

Another consequence of the defeat at Carrhae was that the Romans had to make an invasion in the east to avenge themselves. Mark Antony did this with mixed success, but in the end, it was up to Tiberius to regain the eagle standards of the Roman army, an event exuberantly celebrated in Roman propaganda.

In this period, Harran belonged to a small kingdom called Osrhoene, which was part of the larger Parthian Empire and had nearby Edessa (present-day Şanlıurfa) as its capital. The Roman emperor Lucius Verus (r. 161-169) tried to conquer this kingdom and nearby Nisibis and was successful, but an epidemic broke out and made annexation impossible. However, a victory monument was erected in Ephesus, and Harran is shown as one of the subject towns. The Roman emperor Septimius Severus finally added Osrhoene to his realms in 195. The conic domed houses of ancient Harran, which have remained unchanged until the present day, can be seen on the Arch of Septimius Severus on the Forum Romanum in Rome.

His successor Caracalla gave Harran the status of colonia (214) and visited the city in April 217, because he wanted to visit the temple of Sin. Instead, he was murdered by the prefect of the Praetorian guard, Macrinus, who was to be the new emperor.

The Roman emperor Julian the Apostate sacrificed to Sin in 363, at the beginning of his ill-fated campaign against the Sasanian Persians. From now on, the region was a battle zone between the Romans and Sasanians. It remained Roman (or Byzantine) until 639 when the Muslim armies captured the city.

Although Christianity came early to Harran, many local people long retained their ancient Sabian religion. Harran was a remote enclave where non-Christian philosophers sought refuge and taught in peace. In 639, Muslim Arabs conquered Harran. Then about a century later Caliph Marwan II, the last of the Umayyad dynasty, made Harran the capital of the Islamic Empire stretching from Spain to Central Asia. Marwan II rebuilt the city on an oval plan around a central hill. The town was surrounded with a 4 km long and 3 km wide wall with seven gates, which is still partially intact. Marwan erected a government palace, built irrigation canals and renovated the Ulu Cami (Grand Mosque), which ruins can still be seen today.

Caliph Marwan II reigned from 744 until 750. Marwan, the grandson of the fourth Umayyad Caliph, was born in 688 in Upper Mesopotamia where his father was governor. He lived at a time when the Islamic Empire reached his maximum extent under Umayyad Caliph Hisham (724-743). Historical sources describe Marwan as courageous, intimidating, and intelligent. Caliph Hisham appointed Marwan Governor of Azerbaijan and Armenia where he effectively consolidated Muslim control. Marwan brought Islam to Georgia where he was known as Marwan the Deaf because he did not hear the screams for mercy from his opponents. In 736 Marwan sacked and destroyed the late Roman Black Sea enclave Sebastopolis (Sukhumi), effectively driving the Romans out of Georgia. Beginning in 740 Caliph Hisham faced a Shiite rebellion and Berber revolts in North Africa, which effectively cut off the territory of present-day Morocco and Spain from Umayyad rule.

After Hisham’s dead in 743, a savage power struggle erupted within the Umayyad family. Hisham’s immediate successor, Walid II, known as a libertine poet rather than a warrior, was soon displaced. Three different Umayyad caliphs ruled within a year as the Islamic empire descended into chaos. Marwan seized power in 744. To consolidate his control, Marwan moved the capital from Damascus to Harran, reorganised the army and regained full control of Syria in 746. However, the anti-Umayyad sentiment was widespread, especially in Iran and Iraq, and the rival Abbasids had many sympathisers. In 747 the Abbasids under Abu al-Abbas went into open rebellion in Khurasan (modern Iran). On January 25, 750 the Umayyad and Abbasid armies fought at the Zab River (in modern Iraq). Despite larger numbers, morale was low in Marwan’s army. The Abbasid warriors formed up in a formidable battle line with spears pointed outward. The Umayyad cavalry was torn to pieces, and the Umayyad army turned and fled. More than 300 Umayyad fighters died in the battle. Although Marwan managed to escape to Egypt, he was relentlessly pursued by Abbasid forces and killed on the Nile delta. Abu al-Abbas, who was known as al-Saffah (the Slaughterer), moved the capital from Harran to Baghdad and founded the Abbasid dynasty. The Umayyad prince Abd al-Rahman escaped to al-Andalus (Spain) where he established a local ruling dynasty, which survived for three hundred years.