<P> Yaḥya's sons al - Fadl (766--808) and Ja'far (767--803), both occupied high offices under Harun al - Rashid . </P> <P> The Barmakid family was an early supporter of the Abbasid revolt against the Umayyads and of As - Saffah . This gave Khalid bin Barmak considerable influence, and his son Yaḥyá ibn Khālid (d . 806) was the vizier of the caliph al - Mahdi (ruled 775--785) and tutor of Hārūn al - Rashid (ruled 786--809). Yahya's sons al - Fadl and Ja'far (767--803), both occupied high offices under Harun . </P> <P> Many Barmakids were patrons of the sciences, which greatly helped the propagation of Iranian science and scholarship into the Islamic world of Baghdad and beyond . They patronized scholars such as Gebir and Jabril ibn Bukhtishu . They are also credited with the establishment of the first paper mill in Baghdad . The power of the Barmakids in those times is reflected in The Book of One Thousand and One Nights; the vizier Ja'far appears in several stories, as well as a tale that gave rise to the expression "Barmecide feast". </P> <P> "We know of Yahya ibn Khalid al - Barmaki (d . 805) as a patron of physicians and, specifically, of the translation of Hindu medical works into both Arabic and Persian . In all likelihood however, his activity took place in the orbit of the caliphal court in Iraq, where at the behest of Hārūn al - Rashīd (786--809), such books were translated into Arabic . Thus Khurāsān and Transoxiana were effectively bypassed in this transfer of learning from India to Islam, even though, undeniably the Barmakī's cultural outlook owed something to their land of origin, northern khurasan, and Yahya al - Barmakī's interest in medicine may have derived from no longer identifiable family tradition ." </P>

Who were the barmakids explain their rise and fall