Tahirid dynasty
The Abbasids soon became caught in a three-way rivalry among Coptic Arabs, Indo-Persians, and immigrant Turks. In addition, the cost of running a large empire became too great. The Turks, Egyptians, and Arabs adhered to the Sunnite sect; the Persians, a great portion of the Turkic groups, and several of the princes in India were Shia. The political unity of Islam began to disintegrate. Under the influence of the Abbasid caliphs, independent dynasties appeared in the Muslim world and the caliphs recognized such dynasties as legitimately Muslim. The first was the Tahirid dynasty in Khorasan, which was founded during the caliph Al-Ma'mun's reign. Similar dynasties included the Saffarids, Samanids, Ghaznavids and Seljuqs. During this time, advancements were made in the areas of astronomy, poetry, philosophy, science, and mathematics.