The Umayyads fell in 750 to the Abbasid Caliphate, which quickly asserted itself in Central Asia after winning the Battle of Talas (along the Talas River in modern Talas Oblast, Kyrgyzstan) in 751 against the Chinese Tang Dynasty. This conflict incidentally introduced Chinese papermaking to the Islamic world. The cultural consequences and political ramifications of this battle meant the retreat of the Chinese empire from Central Asia. It also allowed for the rise of the Samanid Empire (819–999), a Persian state centered at Bukhara (in what is now modern Uzbekistan) that nominally observed the Abbasids as their overlords, yet retained a great deal of autonomy and upheld the mercantile legacy of the Sogdians. Yet the Sogdian language gradually declined in favor of the Persian language of the Samanids (the ancestor to the modern Tajik language), the spoken language of renowned poets and intellectuals of the age such as Ferdowsi (940–1020). So too did the original religions of the Sogdians decline; Zoroastrianism, Buddhism, Manichaeism, and Nestorian Christianity disappeared in the region by the end of the Samanid period. The Samanids were also responsible for converting the surrounding Turkic peoples to Islam, which presaged the conquest of their empire in 999 by an Islamic Turkic power, the Kara-Khanid Khanate (840–1212).