Seikilos epitaph
The Seikilos epitaph is the oldest surviving complete musical composition, including musical notation, from anywhere in the world. The epitaph has been variously dated, but seems to be either from the 1st or the 2nd century AD. The song, the melody of which is recorded, alongside its lyrics, in the ancient Greek musical notation, was found engraved on a tombstone (a stele) from the Hellenistic town Tralles near present-day Aydın, Turkey, not far from Ephesus. It is a Hellenistic Ionic song in either the Phrygian octave species or Iastian tonos. While older music with notation exists (for example the Hurrian songs), all of it is in fragments; the Seikilos epitaph is unique in that it is a complete, though short, composition.
Israel in Egypt
For a long time, the earliest known recording of music known to still exist was an excerpt from this oratorio conducted by August Manns. The recording was of several thousand singers singing "Moses and the Children of Israel"  in the Crystal Palace Handel Festival of June 29, 1888, recorded by Col. George Gouraud on Edison's yellow paraffin cylinder. The limitations of recording technology at that time, together with the number of voices, the distance of the recording device from the singers and the acoustics of the Crystal Palace, mean that the recorded sound was dim to begin with, and it has since then become badly degraded. What survives is barely audible but still identifiable by ear, and gives some insight into performance practices at the height of the Handel Festival phenomenon.