Ahmad Ibn Muhammad NakhshabiBokharaieDehlavi, known as Mas'ud Bag, a Persian writer of the 8th and 9th centuries (AH) who turned to mysticism and became a devotee of Chishtitariqat has left behind insightful writings and poetry. Though he is famous outside Iran, especially in India and Pakistan, he is not much known inside Iran. His mystical writings reflect views of such great writers as Ein al-Qozat-e Hamadani, Atar, Sa'di, and a few others. In this paper, the often contradictory narratives of biographies about the life and works of Mas'ud Bag are compared. By referring to his poetry and his books, Mer'at al-'Arefin, a clearer picture of the events of his life and his views is extracted. His name, title, his relations, his ruling of Transoxania, his rejection of the material world, and his connection to the Chishtitariqat are also discussed.