Khosro I, traditionally known by his epithet of Anoushiravan (خسرو انوشیروان) was the Sasanian King of Kings of Iran from 531 to 579. Khosro I was known for his character, virtues and knowledge. During his ambitious reign, he continued his father's project of making major social, military, and economic reforms, promoting the welfare of the people, increasing state revenues, establishing a professional army, and founding or rebuilding many cities, palaces, and much infrastructure. He was interested in literature and philosophy, and under his reign, art and science flourished in Iran. The game of chess reportedly was also brought by him from India. He was the most distinguished of the Sasanian kings, and his name became a designation of the Sasanian kings. The Sassanian revival took place under his rule and as such Khosro minted inscriptions on his especial issue coinage as "Iranians have become fearless" and "Iranians became strong".
Khosro I was reportedly born between 512 and 514 in Ardestan, a town located in current day Isfahan province. He was the youngest son of Ghobad I, the ruling Sasanian king while his mother was an Ispahbudhan princess. The Ispahbudhan were one of the Seven Great Houses of Iran that formed the elite aristocracy of the Sasanian Empire. As such Khosro would have started at school between the ages of five and seven and would learn to write and would be educated according to the same pattern of schooling made for a future priest. Furthermore, he would observe the Middle Persian translation of the Avesta. Afterwards, he would be schooled in riding, archery, polo and military creativity.
In 520, Ghobad, in order to secure the succession of Khosro, whose position was threatened by rival brothers and the Mazdakite sect, proposed that Byzantine Emperor Justin I adopt him. The proposal was rejected due to the concern of Khosro possibly later try to take over the Byzantine throne. Khosro reportedly felt insulted by the Byzantines, and his attitude deteriorated towards them. In 531, while the Iranian army was besieging Martyropolis, Ghobad became ill and died. Khosro succeeded him but had to deal with his eldest brother Kavoos, who ruled as governor-king of the northern province of Padishkhwargar and asserted to be the legitimate heir of the throne due to his older age. He was, however, defeated by Khosro's forces and taken to Ctesiphon, where he refused to ask for forgiveness, preferring death, thus forcing Khosro to have him killed. Another danger to Khosro's rule was that of his uncle Bavi, who became involved in a conspiracy to try to overthrow Khosro and make Ghobad, the son of Khosro's brother Jamasp, the shah of Iran. Upon learning of the plot, Khosro executed all his brothers and their offsprings, along with Bavi and the other aristocrats who were involved. Khosro also ordered the execution of Ghobad, who was still a child, but Adergoudounbades brought him up in secret.
Due to his domestic position being insecure, Khosro wanted to make peace with the Byzantines. The Byzantines found Khosro in a more conciliatory disposition than his father, and an agreement was soon reached. Justinian would pay 110 centenaria (11,000 pounds) of gold, ostensibly as a contribution to the defense of the Caucasus passes against the barbarians living beyond, and the base of the dux Mesopotamiae would be withdrawn from the fortress of Dara to the city of Constantina. The two rulers would recognize once again each other as equal and pledged mutual assistance.
The peace agreement between Rome and Iran gave Khosro the chance to consolidate power and focus his attention on internal improvement. His reforms and military campaigns marked a renaissance of the Sasanian Empire, which spread philosophic beliefs as well as trade goods from the far east to the far west. His reforms resulted in the rise of a bureaucratic state at the expense of the great noble families, strengthening the central government. The army too was reorganized and tied to the central government rather than local nobility allowing greater organization, faster mobilization and a far greater cavalry corps.
Reforms in taxation provided the empire with stability and a much stronger economy, allowing prolonged military campaigns as well as greater revenues for the bureaucracy. Prior to Khosro and Ghobad's reigns, a majority of the land was owned by seven Parthian families: Suren, Waraz, Karen, Ispahbudhan, Spandiyadh, Mihran and Zik who enjoyed tax exemptions from the Sasanian Empire and were tax collectors within their local provincial areas. Khosro surveyed all the land within the empire indiscriminately and began to tax all land under a single program. Prior to Khosro's tax reforms, taxes were collected based on the yield that the land had produced. Tax revenues that previously went to the local noble family now went to the central government treasury. Because the tax did not vary, the treasury could easily estimate the year's revenue.
Khosro, like all other Sasanian rulers, was an adherent of Zoroastrianism. Before, the Sasanian Empire consisted of only three social classes, magi, nobles and peasants/commoners. Khosro added a fourth class to this hierarchy between the nobles and the peasants, called the dehqans. The dehqans were small land owning citizens of the Sasanian Empire and were considered lower nobility. Khosro promoted honest government officials based on trust and honesty, rather than corrupt nobles and magi. The small landowning deghans were favored over the high nobles because they tended to be more trustworthy and owed their loyalty to the Shah for their position in the bureaucracy.
Khosro is known to have ordered many public works projects during his long reign such as bridges, roads, dams and walls. To protect the frontiers of Iran, Khosro had a sequence of walls built (and fortified) around his empire, much like the Great Wall of China and Hadrian's Wall in Northern England. Instead of constructing it on one side of the empire, he had it on four. Khosro ordered the construction of the Great Wall of Gorgan, which extended from the eastern coast of the Caspian Sea to block incursions by nomadic tribes, such as the White Huns. In the northwest, he had the Derbent Wall further fortified to protect the area from incursions by Alans, Turks, Sarirs, Khazars, and other northern neighbors. Another wall was constructed in the southwest and he may have also built another wall in the northeast. Besides defense structures, Khosro also had a large-scale canal system. Out of all his constructions, his most memorable and noteworthy achievement was the palace he had made at Ctesiphon, known as the Tagh’e Kasra. The palace, still standing till this day, albeit heavily ruined, portrays one of the empire's most remarkable architectural accomplishments.
The main force of the Sasanian army was the Aswaran cavalry. Previously only nobles could enlist into the Aswaran cavalry which was very limited and created shortages in well trained soldiers. Now that the dehqan class was considered nobility, they were able to join the cavalry force and boosted the number of cavalry force significantly. A list for equipment for the cavalry was written that included a helmet, a gorget, a chain mail shirt, a lamellar coat or cuirass, leg armor, gauntlets, sword, shield, two bows with spare strings, 30 arrows, axe or mace, and horse armor. Horses were still fully armored during this period and heavy cavalry tactics were still used by the Sasanian cavalry.
In 531, Justinian suggested that the Ethiopians of Yemen end the Sasanians maritime trade with the Indians. The Ethiopians never met this request because an Ethiopian general named Abraha took control of the Yemenite throne and created an independent nation. After Abraha's death one of his sons, Ma'd-Karib, went into exile while his half-brother took the throne. After being denied by Justinian, Ma'd-Karib sought help from Khosro, who sent a small fleet and army under commander Vahrez to depose the current king of Yemen. After capturing the capital city San'a'l, Ma'd-Karib's son, Saif enthroned.
In 539 the Ghassanid ruler al-Harith ibn Jabalah invaded Lakhmid ruler Mundhir's territory and carried off rich booty. Khosro complained to Justinian about this incident and requested that the stolen riches be returned to him, including payment for the Arabs that had been killed during the attack. His request was, however, ignored. In May 540, Khosro invaded the domains of the Byzantines. He approached Zenobia, where he made a lukewarm attempt to persuade the fortress to surrender, which proved unsuccessful. He then proceeded to Sura and killed its commander Arsaces in battle. Demoralized by the death of their commander, the residents sent their bishop to parley with Khosro. Feigning to accept the plea of the bishop, Khosro took advantage of the occasion and captured the city, which was shortly sacked. Khosro continued his expedition, threatening the city of Hierapolis, whose custodians swiftly paid him 2,000 pounds of silver to leave the city untouched. In June, Khosro reached Antioch, where he captured and sacked the city. Justinian sued for peace, and made a treaty with Khosro that the Iranians would withdraw back to their domains in return for a payment of 50 centenaria plus 5 centenaria extra each year. In 549 the previous truce between Justinian and Khosro was disregarded and full war broke out once again between Iranians and Romans. The last major decisive battle came in 556 when Byzantine general Martin defeated a massive Sasanian force. Negotiations between Khosro and Justinian opened in 556, leading to the Fifty-Year Peace Treaty in 562 in which Iranians would leave Lazica in return for an annual payment of gold.
Both Turks and Iranians wanted to dominate the Silk Road and the trade industry between the west and the far east. In 562 Khosro defeated the White Huns once again, and then stopped the threat of the Turks. Khosro then sent a Mihranid named Mihransitad, to estimate the quality of the daughter of the Turkic Khagan. According to Armenian sources her name was Kayen, while Persian sources states that her name was Qaqim-khaqan. After Mihransitad's visit in Central Asia, Khosro married Qaqim-khaqan.
Justinian died in 565 and left Justin II to succeed the throne. Justin II stopped paying annual payments to Khosro, effectively putting an end to the peace treaty that was established ten years earlier. In 573, Khosro sent an army to invade Syria, while he himself along with Bahram Chobin led an army towards Dara, where they captured the city after four months. Justin reportedly lost his mind after these Byzantine disasters and abdicated. Khosro ravaged the places around Resaina and Constantia in Syria. However, the tables of the war quickly turned again when the newly appointed Byzantine supreme-commander Maurice entered the field and captured many Sasanian settlements. The revolt came to an end when Khosro gave amnesty to Armenia and brought them back into the Sasanian Empire. Peace negotiations were once again brought back up, but abruptly ended with the death of Khosro in 579.
At the time of his death, the Sasanian Empire had reached its greatest extent since Shapur II, stretching from Yemen in the west to Gandhara in the east. Although Khosro's achievements were highly successful and helped centralize the empire, they did not last long after his death. The local officials and great noble families resented the fact that their power had been stripped away from them and began to quickly regain power after his death.