 He notes that references to "Tipitaka" and "Nikaya" date from much later periods than the Asokan era (such as Kaniska's reign).Only a few texts have been identified in Asoka's edicts (such as his Bhabra Edict), but these are all short verse texts and are nothing like the suttas of the first and second Nikayas.Schopen concludes that it is only "from the end of the fourth century, that some of the doctrinal content of Hinayana canonical literature can finally be definitely dated and actually verified."