Quran is merely a re-working of an earlier Christian text, a Syriac lectionary. Gerd R. Puin, has similar views about Alexander the Great in the Quran. Fred Donner has argued for an early date for the collection of the Quran, based on his reading of the text itself. He points out that if the Quran had been collected over the tumultuous early centuries of Islam, with their vast conquests and expansion and bloody incidents between rivals for the caliphate, there would have been some evidence of this history in the text. However, there is nothing in the Quran that does not reflect what is known of the earliest Muslim community. In 1972, during the restoration of the Great Mosque of San'a in Yemen, labourers stumbled upon a "paper grave" containing tens of thousands of fragments of parchment on which verses of the Quran were written. Some of these fragments were believed to be the oldest Quranic texts yet found. The latest in origin of the Quran is the discovery of parchments of Quranic text by the University of Birmingham in 2015, the parchment material has been radiocarbon dated to the period between 568 and 645 with 95.4% accuracy. The test was carried out in a laboratory at the University of Oxford. The result places the parchment close to the time of Muhammad, who is generally thought to have lived between 570 and 632. Researchers conclude that the parchment is among the earliest written textual evidence of the Quran in existence. François Déroche of the Collège de France, however, expressed reservations about the reliability of the radiocarbon dates proposed for the Birmingham leaves, noting instances elsewhere in which radiocarbon dating had proved inaccurate in testing Qurans with an explicit endowment date. Mustafa Shah, Senior Lecturer in Islamic Studies at the School of Oriental and African Studies, has suggested that the grammatical marks and verse separators in the Birmingham leaves are inconsistent with the proposed early radiocarbon dates. Textual criticism In the 1970s, what has been described as a "wave of sceptical scholars" challenged a great deal of the received wisdom in Islamic studies. They argued that the Islamic historical tradition had been greatly corrupted in transmission. They tried to correct or reconstruct the early history of Islam from other, presumably more reliable, sources such as coins, inscriptions, and non-Islamic sources. The oldest of this group was John Wansbrough (1928–2002). Wansbrough's works