In Book X Curtius digresses to give an encomium on blessings of peace under empire, citing the Roman Empire with the implication of contemporaneity. In essence he reasserts the policy of Augustus, which casts the empire as the restoration of monarchy for the suppression of the civil wars fomented by the contention of powerful noblemen vying for control of the Republic. Curtius' glowing endorsement of the policy dates him to the Roman Empire. He also mentions the Parthian Empire. It was formed by the eastern satrapies recusing themselves from Macedonian overlordship and restoring a purely Iranian empire. It defended itself successfully against Rome, even though Rome absorbed what was left of the Macedonian kingdoms. The dates of the Parthian Empire are 247 BC through 224 AD. Although Curtius may have been writing about an empire vanished in his own day, the most straightforward approach assumes that he wrote in a window, 63 BC (start of the Roman Empire) through 224 AD. For further localization, the same imperial purple passage contrasts the civil wars of the Macedonians (Diadochi wars) due to failure to obtain a stable emperor, with an incident of the Roman Empire in which the risk of civil war was avoided by the appointment of a new emperor in a single night. Not very many incidents fit the description. Baynham summarizes the argument of Julius Nützell that the crisis might be the night of January 24/25, 41 AD, following the assassination of Caligula on that day. The Senate met on an emergency basis to debate whether the Roman Republic should be restored. The Praetorian Guard forced its way in to insist on the appointment of Caligula's uncle, Claudius. His reign concentrated on the restoration of the rule of law. A lawyer, he issued up to 20 imperial edicts per day, re-establishing the Pax Romana. If this argument is correct, Curtius' work must be dated to after 41 AD. The upper limit is provided by a passage that mentions the "continued prosperity of Tyre under Roman dominion." The peace of the empire came to an end in 43 AD when Claudius invaded Britain. None of these dates are certain, but the union of all the ranges presents a credible view of Curtius' date. Baynham says: "many modern scholars now accept a date in the middle to late part of the first century A.D. as a likely floruit for Curtius." By his name, Quintus Curtius Rufus was a member of the "Curtii Rufi" branch of the Curtii family, one of the original nobility of Rome.