Battle of Belanger The Turko-Arab War In the 7th century AD, the Romans saw two major threats before them. The first was the Avars, who were constantly plundering the lands of the empire. The second and greatest threat was the Sasanian Empire, which had begun anew in 602. With the rise of Khosrow Parviz, the Sasanian relations with the Romans were initially friendly due to the support that Maurice had given Khosrow Parviz. However, when Maurice was deposed and killed by a group of soldiers in a revolt, Khosrow Parviz declared war on the Byzantine Empire under the pretext of revenge. The Sasanian army won successive victories in the early part of the war and took control of many areas of Anatolia, Syria, and Egypt. The Sasanian advance was so great that even Constantinople was on the verge of falling, but the siege of this city was unsuccessful. It was at this time that Heraclius ascended the throne as the savior of the empire. Heraclius initially assessed the situation He improved the chaos of the empire to some extent and then, with the campaigns he conducted, forced the Sassanid armies to retreat to the other side of the Euphrates River. In the meantime, Heraclius asked the Gok Turks to help them against the Sassanid king Khosrow Parviz. In 624 AD, the Roman ambassador came to the Great Khan of the Gok Turks, Tong Yabgu Khan. The Khan looked at this cooperation positively. In this way, the two powers of that time united against the great Sassanid Empire. The Khan prepared an army from around the Caspian Sea and sent it south under the command of his son Burishad Khan. Burishad crossed the Turk River and was quickly able to conquer the city of Darband and several other cities. Later, the Great Khan Tong Yabgu also joined the army. In the meantime, Heraclius' army was around Lazica. In 627 AD, the two rulers besieged the city of Tbilisi together, but Tbilisi, despite being besieged by two great powers at the same time, was surprisingly not conquered! The Sassanid garrisons showed an epic defense of themselves during the siege of this city. Things got to the point where Tong Yabgu Khan became discouraged due to the high resistance of the enemy forces and, despite the secrets that Heraclius had left with him, he handed over the command of the army to his son and returned to his country. On the other hand, Heraclius abandoned the siege of Tbilisi and instead decided to move towards the heart of the Sassanid government, namely Ctesiphon. The Sassanids, who were in a critical situation with numerous defeats, were unable to besiege Heraclius' army, so that Heraclius advanced as far as Ctesiphon. Although Heraclius did not intend to conquer Ctesiphon because he did not have enough siege equipment and there was also the possibility of being trapped on the Sassanid borders, by sending a truce to Khosrow, Khosrow returned, who after lightning and dazzling victories had now suffered heavy defeats from the Romans, stubbornly refused all of Heraclius' peace offers and He blamed all the blame on the generals and commanders and punished them with great care. Ultimately, the disgruntled nobles and generals deposed Khosrow Parviz from the throne, accused him of murder, and then installed his son, Qobad II, on the throne. The reign of Khosrow Parviz was the last glorious reign of ancient Iran. Khosrow's lightning victories against the Byzantines were surprising and astonishing to these proud heirs of ancient Greece. Although he achieved impressive military achievements in the early days and almost brought Byzantium to its knees, in the end, due to his foolishness and short-sightedness, as well as his harshness towards his subordinates and the issuance of cruel and unfair orders against them, he brought the valuable heritage of his fathers' land to a terrible decline and fall in a short time. It is true that Heraclius was a very good commander, but this heavy defeat of the Sasanians was mostly due to Khosrow's mistakes. Khosrow Parviz brought not only himself but also his country to the brink of destruction with his wrong policies. In the eyes of the Byzantines, the war was over, but the Gok Turks wanted to benefit from this fatal blow that had been dealt to the Sasanians. In 627 AD, Tong Yabgu Khan crossed the border and conquered the cities of Darband. And Ganja advanced to the back of the walls of Tbilisi... Sources: History of Tabari - Ancient Turks by Le Gumilo