Sultan Ahmad Khan b. Sardar 'Azim Muhammadzai[1] (Persian: سلطان احمد خان بن سردار عظیم محمدزی), also known as Sultan Jan[2] (Persian: سلطان جان) was the ruler of the Principality of Herat from September 1857 to April 1863. He was a nephew of Dost Mohammad Khan. In 1855-56, Sultan Ahmad Khan sent a petition to the Shah, Nasir al-Din.[3] If the Iranians would support Sultan Ahmad Khan with an army, he would overthrow the Amir-i Kabir and incorporate Afghanistan into the Guarded Domains. However, Sultan Ahmad Khan was intercepted by Dost Mohammad Khan, who exiled Sultan Ahmad Khan to Iran.[3]
After the conclusion of the Anglo-Persian War, he was installed as ruler of Herat by the Iranians. On May 24, 1857, Sultan Ahmad Khan arrived in Herat.[1] The Iranians evacuated Herat in September 1857[1] in accordance with the Treaty of Paris.[4] During Sultan Ahmad Khan's reign, he was completely dependent on Iran and not only minted coins in the Shah's name, but also given assistance against the Muhammadzais to the east.[1] Naser al-Din Shah bestowed the title of Sirkar (Persian: سرکار) on Sultan Ahmad Khan and gave his son, Shah Nawaz Khan, the title of Amir Panji (Persian: امیر پنجی).[5]
Khan captured Farah soon after in March 1862. Farah had been a Muhammadzai possession since their occupation of the town on October 30, 1856.[6][1] This became Dost Mohammad Khan's casus belli to launch an attack on Herat. On June 29[4] or July 8[7] Farah was captured by the Muhammadzais. On July 22,[7]Sabzawar was captured. By July 28, Herat was besieged.[4] During the 10-month siege Ahmad died on March 6, 1863,[1][8] being succeeded by his son Shah Nawaz Khan. Shortly before his death, he had been affected by a disease that causes limb paralysis.[8] On May 27, 1863, Herat would finally fall to the Amir.[4]