The date of the demise, or (Mahapāri)Nirvāṉa, of the historical Buddha Śākyamuni is one of the key chronological markers in early Indian history, one which has therefore been of pivotal importance to modern scholarship on ancient India. Whilst the dates of the conquest of Gandhāara and Sindh by the Achaemenid empire and the dates of Alexander's campaigns in the subcontinent are among the very oldest established for the history of north-western India, that of the Nirvāna of the Buddha has long been regarded as the oldest more or less fixed chronological value in the history of north-eastern India. The dating of the Buddha has a crucial significance for the dates of certain ancient Indian kings-Bimbisara of Magadha and Prasenajit (Pasenadi) of Kosala -and for that of the Jain Tīrthaṅkara Mahāvīra, for the development of Jainism and the Śramaṉa movement, and for the earlier history of the Brahmanical religion and the oldest Indian philosophy, including the thought of the Upaniṣads. Moreover, quite apart from its importance for South Asia alone, the consensus (apparently) obtaining among scholars about the time of the Buddha contributed to the elaboration by Karl Jaspers, in his book of 1955 entitled Vom Ursprung und Ziel der Geschichte, of the concept of an Axial Age (‘Achsenzeit’) around 500 B.C. when a number of epoch-making events are thought to have taken place in the ancient Eurasian world.