The burials were mostly in clay pots. A hole was made in the side of the pot to insert the body, then the pot fragment was placed back.

Some 2700 burials have been excavated but more are buried, perhaps a total of 4,000 or more. This is apparently unique in the world in terms of the number of burials.

Most were of stillbirths or babies that died shortly thereafter (one 3 year old has been found) and date from 600 BCE through to Roman times.

This display is in the island's small archeological museum down by the old port.

Why Astypalaia, which has never had a large population? Speculation is that women came to the island to give birth there because there was a sanctuary to one of the goddess' who protected women giving birth. There are indications from the pots that not all originated in Astypalaia.

It is speculated that the pot is symbolic of the womb and most of the burials were positioned with the head towards the neck of the pot as most (but not all) babies are positioned in the womb. A small percentage of pots have two bodies inside, presumably representing twins.

Work began on this (and a second site) in the 90s.

The only academic article I could quickly find was:

Simon Hillson, "The World's Largest Infant Cemetery and Its Potential for Studying Growth and Development", Hesperia Supplements, v.43 (2009)