Samarkand; Ahmad ibn Asad received Farghana; Yahya ibn Asad received Tashkent, and Ilyas ibn Asad received Herat. Rise The Samanid dynasty in Herat (819–857) Ilyas died in 856, and his son Ibrahim ibn Ilyas became his successor. The Tahirid governor of Khorasan, Muhammad ibn Tahir, subsequently appointed him as the commander of his army, and sent him on an expedition against the Saffarid ruler Ya'qub ibn al-Layth al-Saffar in Sistan. After facing defeat in battle near Pushang in 857, he fled to Nishapur, only to be captured by Ya'qub al-Saffar and sent to Sistan as a hostage. The Samanid dynasty in Transoxiana (819–892) In 839/40, Nuh seized Isfijab from the nomadic pagan Turks living in the steppe. Consequently, he had a wall constructed around the city to protect it from their attacks. He died in 841/2—his two brothers Yahya and Ahmad, were then appointed as the joint rulers of the city by the Tahirid governor of Khorasan. After Yahya died in 855, Ahmad took control over Châch, thus becoming the ruler of most of Transoxiana. He died in 864/5; his son Nasr I received Farghana and Samarkand, while his other son Ya'qub received Châch (areas around modern Tashkent/Chachkent). Meanwhile, the Tahirids' authority had significantly weakened after suffering several defeats to Saffarid ruler Ya'qub al-Saffar. Hence, causing the Tahirids to lose their grip over the Samanids, who became more or less independent. Nasr I, used this opportunity to strengthen his authority by sending his brother Ismail to Bukhara, which was in an unstable condition after suffering from raids by the Afrighid dynasty of Khwarazm. When Ismail reached the city, he was warmly received by its inhabitants, who saw him as one who could restore order. After not so long, disagreement over where to distribute tax money caused a conflict between the brothers. Ismail was eventually victorious in the dynastic struggle and took control of the Samanid state. However, Nasr had been the one who had been invested with Transoxiana, and the Abbasid caliphs continued to recognize him as the rightful ruler. Because of this, Ismail continued to recognize his brother as well, but Nasr was completely powerless, a situation that would continue until his death in August 892. Final unification and height of power (892–907) Following Nasr's death, Ismail moved the capital of the Samanid dynasty from Samarkand to Bukhara. A few months later the Saffarid emir, Ya'qub al-Saffar, also died