Arabic poetry thrived in ninth century Baghdad, as did art, the sciences, and other intellectual pursuits. The Tales of the Arabian Nights (Alf Layla wa Layla, literally, "1,000 Nights and One Night") was compiled during this period. Baghdad became a luxurious, commercial city making the Middle East the center of world trade. There was unprecedented wealth affecting all classes.
In the court of Harun al-Rashid, a new office appeared for the first time in response to the growing complexities of running an ever-expanding commercial, political, and military empire: the office of wizeer ("vizier," or, "minister"). The first vizier was a Persian Buddhist, Khalid al-Barmaki. He served as counselor to the caliph, chief executive, and treasurer. He was succeeded in office by descendants creating a dynasty that in time began to eclipse that of the caliph himself in popularity and power. The Barmakis amassed fabulous fortunes, entertained lavishly, and were extravagantly generous with their wealth. In 803, Harun decided to do something about that. The severed head of the current Barmaki vizier was impaled on one of Baghdad's bridges, while the halves of his bisected body were put on view at the other two bridges. Harun then went on to wipe out the rest of the Barmaki family. However, their name lived on in a famous Arabic proverb: "as generous as a Barmaki!"
While the Barmakis were gone, the office of vizier was there to stay. The caliphs simply could not manage the burgeoning bureaucracy and other machinery of government without it.
In 832, the Bayt al Hikma ("House of Wisdom") in Baghdad was established under the Caliph, Mamun (813-833). The complex included a vast public library, astronomical observatory, and bureau of translation. Greek works (including those of Plato and Aristotle) were translated into Arabic and a world atlas was compiled. The sciences flourished there. Among the other works translated into Arabic were the medical texts of Galen and Hippocrates, Euclid's Geometry, and Ptolemy's astronomical writings. Later, in Muslim Spain, Ibn Rushd Averroes (1126-1198) wrote his commentaries on Aristotle. These commentaries profoundly influenced such prominent western philosophers as the Catholic theologian, Thomas Aquinas.
Original research in medicine was conducted in the Bayt al-Hikma. The Christian physician, Yuhanna, dissected apes. His student, Hunayn, produced a two volume work on the human eye. Al-Razi built a hospital and wrote books on smallpox, measles, and his greatest work, a medical encyclopedia cataloging Greek, Hindu, and Persian medical research. Persian born Abu Ali al-Husayn Ibn Sina ("Avicenna," 980-1037) codified Greek and Arabic medical knowledge into a volume that became the standard medical textbook in Europe as well as the Arab world for five hundred years. The first pharmacies in the world date from this period. Baghdad boasted more than eight hundred registered pharmacists. In the field of astronomy, the length of the solar year was accurately calculated five hundred years before the West was to publicly accept the notion that the earth is round. Arab astronomers also calculated the length of a terrestrial degree at 56 2/3 miles, within one half mile of the correct value. The moon's effects on tides were studied.
Other Arab achievements, generally speaking, include the following. In mathematics, al-Kwarizmi introduced the algebra during the first quarter of the ninth century in his book Kitab al-Jabr wa-l-Muqabala ("The Book of Restoration and Comparison"). The geographer, Yakut, compiled an encyclopedia of geographical knowledge. Arab navigators brought the compass from China and perfected the astrolabe, a kind of sextant. Muslim science produced alcohol, logarithms, and the almanac. New foods, such as apricots, rice, and sugar began reaching Europe thanks to Muslim traders. In 751, the technique for making paper arrived from China. The pointed arch from Persia eventually made its way into Europe (via the Crusaders) as the gothic arch. So did improvements in military armor, the use of carrier pigeons, and the concept of chivalry (which can be traced back to the Bedouin concept of muru'ah, "manliness," an idea embracing the virtues of courage, loyalty, and generosity). About the year 990 in Baghdad, Abu 'l-Farag Muhammad Ibn Ishaq al-Nadim published his encyclopedia al-Fihrist ("The Catalogue").
The first histories of the Medinan period of Islam (the times of the Prophet Muhammad) appeared during the Abbasid era: al-Waqidi, Ibn Hisham, and al-Tabari. Some scholars (A.K.S Lambton and R. S. Humphreys among them) argue that these histories were at least partly colored by the ruling ideologies of the Abbasids, especially with respect to the question of the transference of power. (Go to the Mission of al-Bukayr for more on this.)