The emperor's blessing of Palmyrene authority has been debated; Aurelian's acceptance of Palmyrene rule in Egypt may be inferred from the Oxyrhynchus papyri, which are dated by the regnal years of the emperor and Vaballathus. No proof of a formal agreement exists, and the evidence is based solely on the joint coinage- and papyri-dating. It is unlikely that Aurelian would have accepted such power-sharing, but he was unable to act in 271 due to crises in the West. His apparent condoning of Zenobia's actions may have been a ruse to give her a false sense of security while he prepared for war. Another reason for Aurelian's tolerance may have been his desire to ensure a constant supply of Egyptian grain to Rome; it is not recorded that the supply was cut, and the ships sailed to Rome in 270 as usual. Some modern scholars, such as Harold Mattingly, suggest that Claudius Gothicus had concluded a formal agreement with Zenobia which Aurelian ignored.