Ibn Khordadbeh
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 (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 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.