Ala-ud-Din Hasan Bahman Shah (r. 3 August 1347 – 11 February 1358), whose original name was Zafar Khan, was the founder of the Bahmani sultanate.
His original name was Zafar Khan titled with "Alauddin Bahman Shah Sultan - Founder of the Bahmani Dynasty" with his capital at Gulbarga (Hasanabad) and all his coins were minted at Hasanabad.
Zafar Khan was a Turkic noble in the employ of Muhammad bin Tughluq. His descent is unknown.However, there is a popular legend regarding him narrated by the 17th century poet Ferishta, which says that he was a servant of a Brahmin astrologer named Gangu (Gangadhar Shastri Wabale) of Delhi and he was himself called Hasan Gangu. Historians have not found any corroboration for the legend.
Zafar Khan began his career as a general serving under the Sultan Muhammad bin Tughluq. He was made a governor. In 1347 he was made commander of an army in Daulatabad. On 3 August 1347 Nasir-ud-Din Ismail Shah (Ismail Mukh, whom the rebel amirs of the Deccan placed on the throne of Daulatabad in 1345) abdicated in his favour and he set up the Bahmani Kingdom with its headquarters at Hasanabad (Gulbarga).
On establishing an independent kingdom Zafar Khan took the title of Abu'l-Muzaffar Ala-ud-din Bahman Shah.He gave Ismail Mukh a jagir near Jamkhandi and later conferred to him the highest title of his kingdom, Amir-ul-Umara . But Narayana, a local Hindu chieftain still succeeded in turning Ismail against Bahman Shah for a short period before he poisoned Ismail.
Bahman Shah led his first campaign against Warangal in 1350 and forced its ruler Kapaya Nayaka to cede to him the fortress of Kaulas. His kingdom was divided into four provinces and he appointed a governor for each province.During his reign Hasan fought many wars with Vijayanagar. By the time of his death the kingdom stretched from north to south from the Wainganga River to Krishna and east to west from Bhongir to Daulatabad.
He was succeeded by his son Mohammed Shah I after his death in 1358.