Tahirid dynasty
During Al-Mu'tasim's reign, the Tahirid dynasty continued to grow in power. The Tahirids were exempted from many tribute and oversight functions. Their independence contributed to Abbasid decline in the east. Ideologically, al-Mu'tasim followed his half-brother al-Ma'mun. He continued his predecessor's support for the Islamic Mu'tazila sect, applying brutal torture against the opposition. Arab mathematician Al-Kindi was employed by Al-Mu'tasim and tutored the Caliph's son. Al-Kindi had served at the House of Wisdom and continued his studies in Greek geometry and algebra under the caliph's patronage.