Towards a more accurate definition of Early Datings according to the Muslim Era
The present article is devoted to the problem of correlating the events dated according to the Hegira within the first ten years of the Muslim era to the Julian calendar. Before Islam in Mecca as well as, in all probability, in other regions of the Arabian peninsula, a lunisolar calendar with a periodic intercalation of the additional (13<sup>th</sup>) month was in use. The interdiction to insert that month was unambiguously formulated by the Prophet Muḥammad only in the course of the «Farewell Pilgrimage» at the end of the 10<sup>th</sup> year of the Hegira (in early March of A. D. 632). However, the Muslim tradition extrapolated that prohibition to the first ten years of the Hegira, so that such an approach proved to be reflected all the synchronistic tables. The greatest Mathematician and Astronomer of the medieval Islam Abū Rayḥān al-Bīrūnī was perfectly aware of that inconsistency and paid attention on it in his Canon of Mas’ūd. Nevertheless modern scholars specialized in early Islam, acknowledging in words the use of additional months in the very beginning of the Muslim era, are ignoring that circumstance, while they are dating specific events. Meantime still at the end of the 19<sup>th</sup> century the outstanding German Arabist August Müller tried to correlate, at least approximately, the key episodes of the early Islamic history (the Hegira itself, the battles of Badr and of Uḥud) to our calendar taking into account intercalation. The article also includes criticism of the hypothesis advanced by Oleg G. Bolshakov about the coincidence of the beginning of a year in pre-Islamic Mecca with the winter solstice and in view of the latest discoveries in the field of South Arabian epigraphy its attachment to the vernal equinox is demonstrated.