He is one of our main authorities on the life and times of the Prophet. His family was involved in transmissions of Hadith and Ibn Ishaq followed suit. He left Medina where he was born for good, probably because of the enmity of certain people like the traditionist Malik b. Anas; he eventually settled in Baghdad. Apart from the Sira he is also credited with a Kitab al Khulafa (sometimes called Ta\'rikh al-khulafa\'--A History of the Caliphs ) and a book of Sunan . His reputation seems to have varied considerably among the early Muslim critics; some found him very sound (e.g., al-Zuhri, who spoke of him as \"the most knowledgeable of men in maghazi \"), while others regarded him as a liar in relation to Hadith (e.g., al-Athram, Sulayman al-Taymi, and Wuhayb b. Khalid). However, it is of the utmost importance to realize that the Sira of Ibn Ishaq is not extant in its original form, and is not preserved as a single work.