Roman–Persian Wars in the context of "Surena"

The early Muslim conquests or early Islamic conquests (Arabic: الْفُتُوحَاتُ الإسْلَامِيَّة, romanized: al-Futūḥāt al-ʾIslāmiyya), also known as the Arab conquests, were a series of wars initiated in the 7th century by Muhammad, the prophet of Islam. He established the first Islamic state in Medina, Arabia that expanded rapidly under the Rashidun Caliphate and the Umayyad Caliphate, culminating in Muslim rule being established in Asia, Northern Africa, and Southern Europe over the following century. According to historian James Buchan: "In speed and extent, the first Arab conquests were matched only by those of Alexander the Great, and they were more lasting." At their height, the territory that was conquered by the Arab Muslims stretched from Iberia (at the Pyrenees) in the west to India (at Sind) in the east; Muslim control spanned Sicily, most of the Middle East and North Africa, and the Caucasus and Central Asia.

Among other drastic changes, the early Muslim conquests brought about the collapse of the Sasanian Empire and great territorial losses for the Byzantine Empire. Explanations for the Muslim victories have been difficult to discover, primarily because only fragmentary sources have survived from the period. American scholar Fred McGraw Donner suggests that Muhammad's establishment of an Islamic state in Arabia coupled with ideological (i.e., religious) coherence and mobilization constituted the main factor that propelled the early Muslim armies to successfully establish, in the timespan of roughly a century, one of the largest empires in history. Estimates of the total area of the combined territory held by the early Muslim polities at the conquests' peak have been as high as 13,000,000 square kilometres (5,000,000 sq mi). Most historians also agree that, as another primary factor determining the early Muslim conquests' success, the Sasanians and the Byzantines were militarily and economically exhausted from decades of warfare against each other.

The Roman–Parthian Wars (54 BC – 217 AD) were a series of conflicts between the Parthian Empire and the Roman Republic and Roman Empire. It was the first series of conflicts in what would be 682 years of Roman–Persian Wars.

Battles between the Parthian Empire and the Roman Republic began in 54 BC. This first incursion against Parthia was repulsed, notably at the Battle of Carrhae (53 BC). During the Roman Liberators' civil war of the 1st century BC, the Parthians actively supported Brutus and Cassius, invading Syria, and gaining territories in the Levant. However, the conclusion of the second Roman civil war brought a revival of Roman strength in Western Asia.

Early Christians were heavily persecuted throughout the Roman Empire until the 3rd century. Although Christianity initially emerged as a small Jewish movement in 1st-century Judaea, it quickly branched off as a separate religion and began spreading across the various Roman territories at a pace that put it at odds with the well-established Roman imperial cult, to which it stood in opposition; Christians were vocal in their expressions of abhorrence towards the beliefs and practices of Roman paganism, such as deifying and making ritual sacrifices to the Roman emperor or partaking in other methods of idolatry. Consequently, the Roman state and other members of civic society routinely punished Christians for treason, various rumoured crimes, illegal assembly, and for introducing an alien cult that drove many Roman people to apostasy in favour of Jesus Christ. According to Tacitus, the first wave of organized persecution occurred under Nero (r. 54–68), who blamed Christians for the Great Fire of Rome in 64. A number of mostly localized persecutions occurred during the reign of Marcus Aurelius (r. 161–180). After a lull, persecution resumed under Decius (r. 249–251) and Trebonianus Gallus (r. 251–253). The Decian persecution was particularly extensive, as Decius strived to restore the Roman golden age in part by forcing pagan practices upon the Christian community. Another wave of persecution began under Valerian (r. 253–260), but ceased abruptly after he was captured and taken prisoner by the Sasanian Empire during the Battle of Edessa of the Roman–Persian Wars. Under his successor Gallienus (r. 253–268), whose reign was marred by rapidly escalating military conflicts of the Crisis of the Third Century, the first ever decree of tolerance was issued for Christian practices and places of worship, although it stopped short of recognizing Christianity as a religion with legal status.

Emperor Diocletian (r. 283–305) began the Diocletianic persecution, which was the final and the most severe wave of persecution of Christians by the Roman state. It was enforced until the accession of Galerius (r. 305–311), who issued the Edict of Serdica, and the death of Maximinus Daza (r. 310–313). After Constantine the Great (r. 306–337) defeated his rival Maxentius (r. 306–312) at the Battle of the Milvian Bridge in October 312, he and his co-emperor Licinius issued the Edict of Milan, which decriminalized Christianity and suppressed pagan populations throughout the Roman Empire. In 380, Theodosius I (r. 379–395) issued the Edict of Thessalonica, officially establishing Christianity as the Roman state religion. It was also during the reign of Theodosius I that pagan practices were overtly deemed punishable offenses, which laid the framework for early Byzantine anti-pagan policies.

Roman Armenia refers to the rule of parts of Greater Armenia by the Roman Empire from the 1st century AD to the end of Late Antiquity. While Armenia Minor had become a client state until it was incorporated into the Roman Empire proper during the 1st century AD, Greater Armenia remained an independent kingdom under the Arsacid dynasty. Throughout this period, Armenia remained a bone of contention between Rome and the Parthian Empire, as well as the Sasanian Empire that succeeded the latter, and the casus belli for several of the Roman–Persian Wars. Only in 114 would Emperor Trajan conquer and incorporate it as a short-lived Roman province.

In the late 4th century, Armenia was divided between Rome and the Sasanians, who took control of the larger part of the Armenian Kingdom and, in the mid-5th century, abolished the Armenian monarchy. In the 6th and the 7th centuries, Armenia once again became a battleground between the East Roman Empire (Byzantine) and the Sasanian Empire until both powers were defeated and replaced by the Muslim Caliphate in the mid-7th century.

The siege of Constantinople in 626 by the Sassanid Persians and Avars, aided by large numbers of allied Slavs, ended in a strategic victory for the Byzantines. The failure of the siege saved the empire from collapse, and, combined with other victories achieved by Emperor Heraclius (r. 610–641) the previous year and in 627, enabled Byzantium to regain its territories and end the destructive Roman–Persian Wars by enforcing a treaty with borders status quo c. 590.

The Battle of Carrhae (Latin pronunciation: [ˈkar.rʰae̯]) was fought in 53 BC between the Roman Republic and the Parthian Empire near the ancient town of Carrhae (present-day Harran, Turkey). An invading force of seven legions of Roman heavy infantry under Marcus Licinius Crassus was lured into the desert and decisively defeated by a mixed cavalry army of heavy cataphracts and light horse archers led by the Parthian general Surena. On such flat terrain, the legion proved to have no viable tactics against the highly mobile Parthian horsemen, and the slow and vulnerable Roman formations were surrounded, exhausted by constant attacks, and eventually crushed. Crassus was killed along with most of his army. It is commonly seen as one of the earliest and most important battles between the Roman and Parthian Empires and one of the most crushing defeats in Roman history. According to the poet Ovid in Book 6 of his poem Fasti, the battle occurred on 9 June.

Crassus, a member of the First Triumvirate and the wealthiest man in Rome, had been enticed by the prospect of military glory and riches and decided to invade Parthia without the official consent of the Senate. Rejecting an offer from the Armenian King Artavasdes II to allow Crassus to invade Parthia via Armenia, Crassus marched his army directly through the deserts of Mesopotamia. His forces clashed with Surena's troops near Carrhae. Surena's cavalry killed or captured most of the Roman soldiers. Crassus himself was killed when truce negotiations turned violent, and his death ended the First Triumvirate.