Arab armies were able to quickly conquer territory through the use of advanced tactics and the employment of horse and camel cavalry.  Islamic rulers were very tolerant of conquered peoples, and welcomed conversion to the Islamic faith.  All Muslims must learn Arabic, so they can read the Qur'an, the Islamic holy book.  This common language helped to unite many different ethnic groups within the Islamic empire.  It also made possible the easy exchange of knowledge and ideas.

Golden Age
Islamic civilization experienced a golden age under the Abbassid Dynasty, which ruled from the mid 8th century until the mid 13th century. Under the Abbassids, Islamic culture became a blending of Arab, Persian, Egyptian, and European traditions.  The result was an era of stunning intellectual and cultural achievements.

Arts & Architecture
According to the teachings of the Qur'an, Islamic artists were forbidden from using  human figures in religious art. Therefore, they developed a style of geometric shapes and patterns that were used to decorate religious buildings called Mosques.  These geometric patterns usually contained verses from the Qur'an written in a stylized form of decorative handwriting called calligraphy. 

Non-religious artists were allowed to use human figures.  This type of work most often appears in scholarly works of science or literature, which were lavishly illustrated.

Islamic architects borrowed heavily from the Byzantine Empire which used domes and arches extensively throughout their cities. An example of this use can be seen in the Dome of the Rock, a famous mosque in Jerusalem.

Math & Science
Islamic scholars studied both Greek and Indian mathematics before making important contributions of their own. The most well known Islamic mathematician was al-Khwarizimi, who pioneered the study of algebra.  His textbook on the subject became a standard in European universities for centuries.

Islamic scholars were also skilled in astronomy.  They studied eclipses, the rotation of the planets, and calculated the circumference of the earth to within a few thousand feet.

Medicine
Many advances were also made in the field of medicine.  Physicians and pharmacists were required to pass exams before treating patients.  They setup hospitals that had separate areas for trauma cases, this is the basis for today's emergency rooms.  Physicians developed treatments for cataracts, used a variety of herbal remedies, and were adept at treating a variety of injuries. Islamic pharmacists were the first to mix sweet tasting syrups with medicine, ensuring that they would be taken.  

Ibn Sina, a famous Islamic physician, wrote a book called Canon on Medicine, which was an encyclopedia of Greek, Arabic, and his own knowledge of medicine. This book became the standard medical text in Europe for over five hundred years.