Attar means druggist or perfumer, and it was his trade rather than a title. He kept a pharmacy in Nishapur, and the tradition says he attended to a very large number of patients, which he described afterwards as the education that mattered. He does not appear to have had a Sufi master in the ordinary sense; he read, and he collected.
What he collected became the Tadhkirat al-Awliya, the Memorial of the Saints, a prose work of some ninety odd lives of the early Sufis. It is not a critical history and does not pretend to be. It is the channel through which most of what is popularly known about Rabia, about Bayazid and about al-Hallaj reached later readers, and for several of those figures it is effectively the earliest connected account in existence, written three or four centuries after them. Any modern account of the early tradition has to use it and has to say what it is.
His own corpus is a problem of the same kind in reverse. A large number of works circulated under his name, and several long attributed to him have since been assigned to other poets, so that the boundary of what he actually wrote has moved considerably. He is said to have died in the Mongol sack of Nishapur in 1221, an end which suits the poetry rather too neatly and which the sources report without corroborating.