History
Umar appointed Hudheifa to the command of the campaign. Hudheifa first marched to Zanjan. The local garrison defended itself but was eventually overpowered and the city fell.
The Muslim forces proceeded to Ardabil where the Persians did not resist and surrendered on the usual terms of Jizya (the annual tax levied on non-Muslims). From Ardabil, the Muslim forces marched northward along the western coast of the Caspian Sea. A confrontation ensued at the Bab area which was an important port on the Caspian Sea. The Muslims scored another victory, but for unknown reasons, Hudheifa was recalled.
The Persians then launched a counterattack, causing the Muslims to abandon their forward posts in Adurbadagan. As a response, Umar sent expeditionary forces to Adurbadagan, one led by Bukayr ibn Abdallah and another by Utba bin Farqad. The contingent under Bukayr confronted the Persians at Jurmizan. The Persians were commanded by Espandiyar. The battle was quite severe, the Persians were defeated and their commander Espandiyar was captured alive. Espandiyar asked Bukayr, "Do you prefer war or peace?" to which Bukayr replied that the Muslims preferred peace. Espandiyar thereupon said, "Then keep me with you till I can help you in negotiating peace with the people of Adurbadagan". The Persians went to nearby hill forts and shut themselves within. The Muslims captured the entire area in the plains. [2]
During the year of 25 AH, the Mushaf Uthmani of Quran was created in an attempt to avoid linguistic confusion of Qur'an which had been translated to local dialect of Adurbadagan and Armenia. Hudhaifa warned Uthman that the translation would lose its original Tafseer if it failed to standardise in the original Mushaf version first, before the locals could translate and give commentary. [3]
The Muslim conquest of Persia, also called the Muslim conquest of Iran, the Arab conquest of Persia, or the Arab conquest of Iran, was a major military campaign undertaken by the Rashidun Caliphate between 632 and 654. As part of the early Muslim conquests, which had begun under Muhammad in 622, it led to the fall of the Sasanian Empire and the eventual decline of Zoroastrianism, which had been predominant throughout Persia as the nation's official religion. The persecution of Zoroastrians by the early Muslims during and after this conflict prompted many of them to flee eastward to India, where they were granted refuge by various kings.
Al-Miqdad ibn Amr al-Bahrani, better known as al-Miqdad ibn al-Aswad al-Kindi or simply Miqdad, was one of the companions of the Islamic prophet Muhammad. His kunya was Abu Ma'bad. Miqdad was born in Eastern Arabia. He became fugitive in his hometown and ran to Mecca, where he served Aswad al-Kindi. Miqdad managed to gain favor of his master, who in turn adopted him as his son.
The Battle of the Bridge or the Battle of al-Jisr was fought at the bank of the Euphrates river between Arab Muslims led by Abu Ubaid al-Thaqafi, and the Persian Sasanian forces led by Bahman Jaduya. It is traditionally dated to the year 634, and was the only major Sasanian victory over the Rashidun Caliphate army.
The Battle of Hazir or Ma'arakah al-Haadhir took place between the Byzantine army and the Rashidun army's elite cavalry, the Mobile guard. It took place in June 637, three miles east of Qinnasrin at Al-Hadher in present-day Syria.
The Battle of Ayn al-Tamr took place in modern-day Iraq (Mesopotamia) between the early Muslim Arab forces and the Sassanians along with their Arab Christian auxiliary forces. Ayn al-Tamr is located west of Anbar and was a frontier post which had been established to aid the Sassanids.
The Muslim conquest of the Levant, or Arab conquest of Syria, was a 634–638 CE invasion of Byzantine Syria by the Rashidun Caliphate. A part of the wider Arab-Byzantine Wars, the Levant was brought under Arab Muslim rule and developed into the provincial region of Bilad al-Sham. Clashes between the Arabs and Byzantines on the southern Levantine borders of the Byzantine Empire had occurred during the lifetime of Muhammad, with the Battle of Muʿtah in 629 CE. However, the actual conquest did not begin until 634, two years after Muhammad's death. It was led by the first two Rashidun caliphs who succeeded Muhammad: Abu Bakr and Umar ibn al-Khattab. During this time, Khalid ibn al-Walid was the most important leader of the Rashidun army.
The Battle of Ullais was fought between the forces of the Rashidun Caliphate and the Sasanian Persian Empire in the middle of June 633 AD in Iraq, and is sometimes referred to as the Battle of Blood River since, as a result of the battle, there were enormous amounts of Persian Sasanian and Arab Christian casualties.
Umar was the second Rashidun Caliph and reigned during 634–644. Umar's caliphate is notable for its vast conquests. Aided by brilliant field commanders, he was able to incorporate present-day Iraq, Iran, Azerbaijan, Armenia, Georgia, Syria, Jordan, Palestine, Lebanon, Egypt, and parts of Afghanistan, Turkmenistan and south western Pakistan into the Caliphate. During his reign, the Byzantines lost more than three fourths of their territory and in Persia, Umar became the king (ruler) of Iran after the fall of the Sassanid Empire.
The Battle of the Iron Bridge was fought between the Muslim Rashidun army and the Byzantine army in 637 AD. The battle took its name from a nearby nine-arch stone bridge spanning the Orontes River which had gates trimmed with iron. It was one of the last battles fought between the Byzantines and Rashidun Caliphate in the province of Syria. The aftermath of the battle marked the nearly complete annexation of the province into the Rashidun Caliphate with the fall of its capital, Antioch.
The Rashidun Caliphate was the first caliphate to succeed the Islamic prophet Muhammad. It was ruled by the first four successive caliphs of Muhammad after his death in 632 CE. During its existence, the empire was the most powerful economic, cultural, and military force in West Asia and Northeast Africa.
Abū ʿAbd al-Raḥmān ʿAbd Allāh ibn ʿĀmir ibn Kurayz was a Rashidun politician and general. He served as the governor of Basra from 647 to 656 AD, during the reign of Rashidun Caliph Uthman ibn Affan. Through his father, he was a cousin of the Caliph. He is renowned for his administrative and military prowess, particularly for his successful campaigns of reconquest and pacification in the former territories of the Sasanian Empire, in what is now present-day Iran and Afghanistan.
The Rashidun army was the core of the Rashidun Caliphate's armed forces during the early Muslim conquests in the 7th century. The army is reported to have maintained a high level of discipline, strategic prowess and organization, granting them successive victories in their various campaigns.
The 3rd Rashidun Caliph, Uthman continued the policy of military expansion carried out by his predecessors, Umar and Abu Bakr. During his reign, the caliphate stretched from Tripolitania, Egypt, and Anatolia to Greater Khorasan and Sindh and reached its greatest extent in 654 CE. However, these conquests were halted when a rebellion began in Egypt which led to his murder, and began the first Fitna.
'Ubadah ibn al-Samit was a companion of Muhammad and a well-respected chieftain of the Ansar tribes confederation. He participated in almost every battle during Muhammad's era. His official title, according to Muslim scholarly tradition, was 'Ubadah bin Saamit al-Ansari al-Badri for his actions at the Battle of Badr. He served under the first three Rashidun caliphs in the Muslim conquest against the Byzantines.
The Battle of Rasil was fought between the Rashidun Caliphate and the Rai kingdom ruled by Raja Rasil in early 644. It was the first encounter of the Rashidun Caliphate in the Indian subcontinent. The exact location of the battle is not known, but historians suggest it was fought on the western bank of the River Indus.
The Battle of Jalula was fought between the Sasanian Empire and the Rashidun Caliphate soon after conquest of Ctesiphon.
Arfajah ibn Harthama al-Bariqi was a companion of the Islamic prophet Muhammad. He was a member of the Azd branch of the Bariq clan that inhabited Southwestern Arabia.
Al-Qaʿqāʿ ibn ʿAmr ibn Mālik Al-Tamīmī was an Arab Muslim commander and general in the Rashidun army who belonged to the tribe of Banu Tamim. He and his tribe converted to Islam possibly during the time of Ahnaf ibn Qais. He is known as a successful military commander who took part in two important victorious battles in the early Muslim Conquest, the Battle of Yarmouk against the Byzantine Empire and the Battle of al-Qadisiyyah against the Sassanian Empire which was led by Sa`d ibn Abi Waqqas. The Caliph Abu Bakr praised him as an equal to eleven thousand men so in return the caliph's successor, caliph Umar, only sent Qaʿqāʿ and a handful of bodyguards in the first wave of reinforcements to Al-Qadissiyah. Qaʿqāʿ was one of the most illustrious military figures of his era.
Bukayr ibn Abdallah was an Arab military leader, who served the Rashidun Caliphate and is known for the conquest of the Sasanian province of Adurbadagan.
Dhiraar ibn al-Khattab was a warrior participating in the early Islamic conquests. Dhiraar's father, al-Khattab bin Mirdas bin Kathir, was the head of the Banu Fihr clan of Quraish subclan are found throughout his works. Khattab bin Mirdas has lineage through their grandfather, Fihr ibn Malik, with the Prophet. His mother was Hind bint Malik Umm Dhiraar bint Amr, and His uncle was Hafs bin Mirdas.
Rashidun Caliphate 
Sasanian Empire