conducted fertility rites on "water filled goat skins

The earliest use of a waterbed can be traced back to over 3,000 years ago when Persians and Egyptians conducted fertility rites on "water filled goat skins."


Hi,
I couldn't google the pictures of the bolded part in the above, so I'm all at seas as for its meaning. Could you explain it in a few words? Thanks.

You take a goat's skin, sew its edges together tightly, then fill it with water.

You do this to a number of goat's skins.

You then use these as the bed on which a man and a woman get together in a ceremony to increase the fertility of the land.

Thanks, Anglika, for the concise explanation.
Got it.