The Islamic Golden Age or Golden Age of Islam was spurred on by conquests resulting in the collections of Greek manuscripts held within Arab-controlled areas, and the founding of the city of Baghdad which became a center for Muslim science and learning.
After the Prophet Muhammad died in 632, his successors ruled over a growing Islamic empire. In 744, civil war broke out after the murder of caliph al-Walid (668-715), a member of the Umayyad family which had ruled form Damascus since 661. The civil war ended when the Abbasids managed to pacify the empire through military assistance and force. The second Abbasid caliph, Al-Mansur (714-775), founded the city of Baghdad in 762 on a site largely selected because of its good location on the trade route between Persia, Arabia, and the Mediterranean. The caliph’s palace and governmental offices were constructed in the city, thus moving the caliphate from Damascus to Baghdad. This move was followed by a flourishing of science, art, and culture under the Abbasids who focused on projects often ignored by the previous Umayyad Empire. The Abbasids spent more time advancing knowledge and consolidating Islamic rule than on campaigns of conquest. This allowed Arab and Islamic thinkers to explore ideas within foreign works, rather than solely relying on the guidance of the Qur’an and Hadith (the sayings of the prophet Muhammad).
The caliphs Harun al-Rashid (r. 786-809) and al-Mamun (r. 813-833) established the House of Wisdom (Bayt al Hikma) in Baghdad which became a home to an ever growing library of texts, as well as an academy for scholars to translate scientific works into Arabic. The Nestorian Christian, Hunayn Ibn Ishaq (808-873), was a leading scholar in this academy who translated over 100 mostly medical and philosophical works, including those of Plato, Aristotle, Galen, and the neoplatonists. Thabit ibn Qurra (836-901) was also influential having translated ancient Greek works on geography, mathematics, and physics. The ability to translate texts was an advanced skill, and one that greatly aided Arab scientific progress. A sign of this was in a gift the caliph Harun al-Rashid sent to Frankish ruler Charlemange (742-814) in the form of a water clock that sounded the hours by dropping brass balls onto cymbals at the mechanism’s base. This device was one of several technological advancements made by Arabs during this period.
There was also an openness and tolerance within the early Abbasids who allowed thinkers of other faiths to visit their courts. This included Hindu scholars who assisted in calculation techniques by bringing with them India’s relatively advanced mathematics, such as trigonometry used to solve algebraic equations. One scholar of the House of Wisdom, Al-Khwrizimi (730-830) adopted the Hindu use of decimal notation, which he describes in his Book of Addition and Subtraction According to Hindu Calculation. Further progress included the calculation of the square root, calculations based upon astronomical observation, and the adopting and refining of Ptolemy’s view that the Earth is at the center of the solar system and that the planets rotated around it along the lines of eight spheres. In the mid 8th century Muslim scholars adopted the astrolabe, an instrument in which the celestial sphere is projected onto a flat plane marked with latitude and longitude lines. Within three centuries, Islamic astronomy was at its highest point, illustrated by the construction of an observatory at Maragha (eastern Iran) in 1259, and the use of mechanical clocks to assist recording details in finer details.
Other scholars produced new theories, such as Ibn al-Haytham (965-1040), who theorized that sight is the result of light traveling from an object to the eye, Muhammad ibn Zakariya al-Razi (854- c. 932), who produced the first description of measles and smallpox, and Ibn Sina (980-1037) (known in the west as Avicenna), the author of Canon of Medicine. A philosophical school in south western Iran became a center of medical scholarship while the first Islamic hospital was established in Baghdad in the year 800. The Golden Age of Islam came to an end in 1258 with the Mongol invasion of Baghdad, including the destruction of the House of Wisdom.
Bishop's Encyclopedia of Religion, Society and Philosophy 
[…] Despite its negative reputation (and often referred to as the Dark Ages), historians have found the Early Middle Ages to also have been a time of development and progress. For one, it witnessed the rise of Islam in the 7th century, which grew strong after the death of the prophet Muhammad in 632 when Muslim armies begun conquering new territories. Armies invaded Roman Palestine, Roman Egypt, Syria, Mesopotamia, and parts of Asia Minor, while also conquering a number of European lands such as Cyprus, Crete, Malta, areas in the south of Italy, and much of the Iberian Peninsula. This expansion was accompanied by intellectual progress within the Islamic territories under the Abbasid empire where prominent Arab thinkers penned numerous philosophical, scientific, and poetic works (see the Golden Age of Islam). […]
[…] philosophy apart from Stoicism. Greek philosophy continued to live on in the Arab world (see the Gold Age of Islam) where it was preserved on manuscripts and would later resurface in the medieval […]