Back to 9th century, western efforts on knowing Islam and Sīra of Prophet have been started. But, actual researches on this context occurred at last half of 19th century. As a diversion which appeared since the very beginning, two approaches represented. (1) Extremist view based on ignoring historical value of Haḍīth in search of history of Qūran, Sīra and early period of Islamic history, which leaded by Lammens and Caetani. (2) Moderate view of Nöldke and Becker which dedicated on purifying “historical Kernel” of Haḍīth. With efforts of remarkable scholars such as Goldziher, Schacht and Montgomery Watt, those vis-à-vis approaches came to 21th century. In that time, extreme skepticism emerge by Wansbrough and widespread on basis of Crone and Cook’s works. On the other side, scholars like Watt, Serjeant and Kister devote their efforts on inventing some new methods in search for “historical kernel” of Haḍīth and Sīra. Although archeological findings of Negev desert disprove many skeptical views about reliability of Haḍīth, there is still an overt dissension between ‘Sanguine’ or traditionalist and ‘Revisionist’ or sceptics. Thus, I in this study focused on presenting an accurate story of formation and conformation of those two different approaches and also analyzing their methods and positions about authenticity and reliability of Haḍīth in Sīra studies.