During the Abbas era, Arab music entered its glorious era, and singers emerged in endless streams. During the Mahdi's reign, Shaytou from Mecca and Ibrahim from Mosul were quite talented in music. It is said that Xie Yatu's singing can make a chilly person feel warmer than a hot bath; Ibrahim even discovered that when he was directing dozens of musicians to play the pipa, he discovered that one of them did not pull the second string tightly enough. . Later, Ibrahim became Harun's guest, received courtesy from the Caliph, and often received considerable rewards. During this period, music theory also made great progress in the Arab world. Muslims translated Greek music works into Arabic, and some Greek works on music theory were also translated into Arabic and widely circulated. Baghdad musician Yishag al-Musiri wrote several books summarizing music theory and creative practice, and discussing the composition of melody and rhythm. The famous scholar Al-Farabi conducted in-depth discussions on the structure, melody and rhythm of music, and wrote the "Encyclopedia of Music" and "Rhythm Classification", which were regarded as authoritative works of music theory by the people at the time and had a certain influence on Western music.