who rose to favour under Al-Ma'mun. According to Ibn Khordadbeh, the Shah of Kabul had to send 2,000 Oghuz slaves worth 600,000 dirhams as annual tribute to the governor of Khorasan Abdallah ibn Tahir (r. 828-845). In addition to the Oghuz slaves, he also had to pay an annual tribute of 1.5 million dirhams. Mid-9th century, one of their tributaries Abu Da'udid or the Banijurid Amir Da'ud b. Abu Da'ud Abbas, undertook an obscure campaign into eastern Afghanistan and Zabulistan that was profitable. It is recorded that in 864 Muhammad ibn Tahir sent two elephants captured at Kabul, idols and aromatic substances to the caliph. Saffarids Ya'qub b. al-Layth The Tahirid rule was overthrown by Ya'qub ibn al-Layth al-Saffar of Sistan, the first independent Iranian ruler in the post-Islamic era. He also fought against the Abbasid Caliphate. He joined the 'ayyar band of Salih b. al-Nadr/Nasr, who was recognised as Bust's amir in 852. al-Nasr aimed at taking over whole of Sistan and drove out the Tahirid governor in 854, with Sistan ceasing to be under the direct control of the Caliphate. al-Nasr himself was overthrown by Dirham b. Nasr who was overthrown by Ya'qub in 861. Ya'qub and his brother Amr advanced as far as Baghdad and to Kabul itself in eastern Afghanistan with their dynamism, advancing along the historic route taken by the modern Lashkargah-Qandahar-Ghazni-Kabul road. Their eastern campaigns are documented by Arabic sources of Al-Masudi's Murūj adh-dhahab, Ibn al-Athir's al-Kāmil fi't-tā'rīkh and Tarikh-e-Sistan. The Persian historian Gardizi's Zain al-akhbār also mentions the Saffarid campaigns. Salih fled to ar-Rukhkhaj or Arachosia, where he received the help of the Zunbil. Both Salih and the Zunbil were killed by Ya'qub in 865. Abu Sa'id Gardezi mentions that Ya'qub advanced from Sistan to Bust and occupied the city. From here he advanced to Panjway and Tiginabad (two of the chief towns of Arachosia), defeating and killing the Zunbil, though the date is not given. This account matches with that of Tarikh-e-Sistan. Satish Chandra states that, "We are told that it was only in 870 AD that Zabulistan was finally conquered by one Yakub who was the virtual ruler of the neighbouring Iranian province of Siestan. The king was killed and his subjects were made Muslims." Muhammad Aufi's Jawami ul-Hikayat meanwhile states that during his invasion of Zabul, Yaqub employed a ruse to surrender after being allowed to pay homage to the