This manuscript, created in Egypt circa. 400 CE, is a Coptic musical score that demonstrates Ptolemy’s theory of Harmonia Mundi (“Harmony of the World”), in which he coordinated the twelve Zodiac signs with a twelve-tone musical scale. The coloured circles represent chromatic tones while their circumference indicates duration and rhythm. At the top of the manuscript (not pictured) is the Greek inscription συγχορδία πνευματικός, which means ‘spiritual harmony’ (lit: spiritual chord). For more information see Theresa Sauer’s Notations 21, pages 290-291.
It is considered to be the world’s oldest surviving (graphic) musical score, though there are chant and ritual song manuscripts that are older, such as this 2nd century Greek parchment:
Portable Buddhist chant/sutra (scripture) cloths have also been around for longer as well, though it is debatable whether a tonal chant is “music” in the strictest sense of the word:
(Korean Buddhist scripture cloth I purchased at Haeinsa Temple in Daegu)
Shingon Buddhist monks, too, have been using graphic notation to organise their esoteric chant known as shomyou: