The prolonged Byzantine-Sassanid Wars, most importantly the climactic Byzantine-Sassanid War of 602-628, as well as the social conflict within the Sassanid Empire, opened the way for an Arab invasion to Iran in the 7th century. Initially defeated by the Arab Rashidun Caliphate, Iran came under the rule of the Arab caliphates of Umayyad and Abbasid. The prolonged and gradual process of the Islamization of Iran began following the conquest. Under the new Arab elite of the Rashidun and later the Umayyad caliphates, both converted (mawali) and non-converted (dhimmi) Iranians were discriminated against, being excluded from the government and military, and having to pay a special tax called Jizya. Gunde Shapur, home of the Academy of Gunde Shapur which was the most important medical center of the world at the time, survived after the invasion, but became known as an Islamic institute thereafter.
What academy was the most important medical center of the world at the time and became Islamicized after the Arab invasions?
Academy of Gunde Shapur

Other sections of society included the nobility, clergy, and townsmen. Nobles, both the titled nobility and simple knights, exploited the manors and the peasants, although they did not own lands outright but were granted rights to the income from a manor or other lands by an overlord through the system of feudalism. During the 11th and 12th centuries, these lands, or fiefs, came to be considered hereditary, and in most areas they were no longer divisible between all the heirs as had been the case in the early medieval period. Instead, most fiefs and lands went to the eldest son.[R] The dominance of the nobility was built upon its control of the land, its military service as heavy cavalry, control of castles, and various immunities from taxes or other impositions.[S] Castles, initially in wood but later in stone, began to be constructed in the 9th and 10th centuries in response to the disorder of the time, and provided protection from invaders as well as allowing lords defence from rivals. Control of castles allowed the nobles to defy kings or other overlords. Nobles were stratified; kings and the highest-ranking nobility controlled large numbers of commoners and large tracts of land, as well as other nobles. Beneath them, lesser nobles had authority over smaller areas of land and fewer people. Knights were the lowest level of nobility; they controlled but did not own land, and had to serve other nobles.[T]
In what centuries did fiefs become hereditary?
11th and 12th

Qutb Shahi architecture of the 16th and early 17th centuries followed classical Persian architecture featuring domes and colossal arches. The oldest surviving Qutb Shahi structure in Hyderabad is the ruins of Golconda fort built in the 16th century. The Charminar, Mecca Masjid, Charkaman and Qutb Shahi tombs are other existing structures of this period. Among these the Charminar has become an icon of the city; located in the centre of old Hyderabad, it is a square structure with sides 20 m (66 ft) long and four grand arches each facing a road. At each corner stands a 56 m (184 ft)-high minaret. Most of the historical bazaars that still exist were constructed on the street north of Charminar towards Golconda fort. The Charminar, Qutb Shahi tombs and Golconda fort are considered to be monuments of national importance in India; in 2010 the Indian government proposed that the sites be listed for UNESCO World Heritage status.:1118
The government of India proposed that The Charminar become a UNESCO World Heritage site, what other two monuments were suggested for the same status?
Qutb Shahi tombs and Golconda fort