The Abbasid Caliphate brought Islamic civilization to its highest point. It was founded by As-Saffah in 750, but was properly stabilized by his successor Al-Mansur, who also founded Baghdad. During his rule, an embassy of Indian scholars brought the influential work Brahmasphutasiddhanta, which contained information on how to calculate with negative numbers and with zero and introduced the Hindi numeral system to the Arab world (this is the numeral system we use to this day! 0-1-2-3-4-5-6-7-8-9)

His successor Al-Rashid (who is depicted in the post as one of the stars of the "1001 nights" fairytales) and his son Al-Mamun founded the House of Wisdom to which they invited intellectuals from many of its surrounding cultures.

Al-Mamun went to great lengths to collect works of science. In a peace deal with the Eastern Roman Empire (the Byzantine Empire), he acquired the highly valued "Algamest", a work about the motion of the planets in the solar system by the Greek philosopher Ptolemy. Ptolemy's system could accurately predict the complex motion of the planets. Only in the 15th century did Copernicus manage to improve on the system.

the great world history book stephan dinkgreve abbasid caliphate islamic golden age baghdad moorish spain reconquista caliph al-mamun al-rashid ptolemy

"The Great World History Book"