The earliest surviving fragments of the writings on music by the fourth century BCE Greek peripatetic philosopher and writer on harmonic theory, music and rhythm, Aristoxenus (Ἀριστόξενος) of Tarentum (Taranto), Italy) are papyri found at Oxyrhynchus.
"Perhaps the most amazing papyrus fragment is a large excerpt from Aristoxenus' Rhythmica, a part of which was first published in 1898 as fragment 9 of the Oxyrhynchus Papyri. In 1968 it was revealed that fragment 2687 of the Oxyrhynchus Papyri completed columns 2-4 by supplying fourteen or fifteen lines at the bottom; this same fragment added substantially to columns 1 and 5. Nearly one hundred lines of the text have now been uncovered in papyrus dating from the third century C.E. But this is not all. Fragments 667 and 3706 of the Oxyrhynchus Papyri preserve in characteristic Aristoxenian language an analysis of conjunct and disjunct scales and of genera. These fragments, too, date from the second or third centuries C.E. and may very well contain parts of the sections of Aristoxenus' Harmonica missing in the manuscript tradition" (Mathiesen, "Hermes or Clio? The transmission of Ancient Greek Music Theory", Palisca, Baker, Hanning [eds.] Musical Humanism and its Legacy. Essays in Honor of Claude Palisca  5-6).