The circumstances of an-Nasai's death are the least settled part of his biography. The most often repeated account places his final years in Damascus, where he is said to have composed a book setting out the merits of Ali, the fourth caliph, at a time and place where Umayyad-era sympathies still ran the other way, and to have been beaten by a hostile crowd as a result, dying not long afterward from the injuries. Some versions of the story place his death in Mecca instead, to which he is said to have been carried after the attack, and other biographical sources are considerably more cautious about the whole episode, noting that it appears in later compilations rather than in anything closer to his own lifetime.
The atlas records the account as reported rather than as settled fact, because the sourcing is exactly the kind the field itself is built to be suspicious of: a dramatic anecdote, attached to a revered compiler, appearing generations after the events it describes, without an isnad of its own that would meet the standard an-Nasai applied to the hadith he collected.
What is not in dispute is the book's standing. Sunan an-Nasai has been read as one of the six canonical Sunni collections for many centuries, and its reputation for careful narrator criticism has survived every uncertainty about the last chapter of its compiler's life.