He was the third son of Mohammad Afzal Khan, and grandson of Dost Mohammad Khan. Abdur Rahman Khan re-established the writ of the Afghan government after the disarray that followed the second Anglo-Afghan war. He became known as The Iron Amir after defeating a number of rebellions by various tribes who were led by his relatives.

Before his death in Herat, on June 9, 1863, Abdur Rahman's grandfather, Dost Mohammad Khan, nominated his third son, Sher Ali Khan, as his successor, passing over the two elder brothers, Afzal Khan and Azam Khan. At first, the new Amir was quietly recognized. But after a few months, Afzal Khan raised an insurrection in the north of the country, where he had been governing when his father died. This began a fierce internecine conflict for power between Dost Mohammad's sons, which lasted for nearly five years. The Musahiban are descendants of Dost Mohammad Khan's older brother, Sultan Mohammad Khan Telai.

Abdur Rahman distinguished himself for his ability and energetic daring. Although his father, Afzal Khan, who had none of these qualities, came to terms with the Amir Sher Ali, the son's behaviour in the northern province soon excited the Amir's suspicion, and Abdur Rahman, when he was summoned to Kabul, fled across the Oxus into Bukhara. Sher Ali threw Afzal Khan into prison, and a serious revolt followed in southern Afghanistan.

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