These early forms of “magic” were used to protect people’s houses, farms, workshops and cemeteries from any evil influence.
Devil-trap bowls (also known as “incantation bowls” or simply “magic bowls”) are, in a way, not that different from the blessings we might nowadays hang on a wall or behind the main door to our home. Chaldeans, Zoroastrians and Jews would bury these bowls, face down, to keep demons at bay (some would also place them in the threshold, or in any corner of the house). Even Middle Eastern Christians (in particular, Syriac Christians) would keep one or more of these in their own homes.
At least, that was the case around 1,200 to 1,500 years ago, give or take.
The bowls were inscribed in a spiral, from the rim to the center, generally in either Hebrew or Aramaic. The inscription included a blessing for the house (or the owner of the bowl) and a reprimand addressed to any demon who would dare threatening the peace of that house. Syriac Christians would use the Syriac alphabet instead in their inscriptions. Most of these bowls, though, were produced by Jewish communities in Babylon living under the rule of the Sassanian Empire, but some non-Jewish communities (mostly Zoroastrians) would also use these bowls quite commonly.
Nowadays, “devil-trap” bowls constitute an important archaeological source of historical knowledge regarding Jewish, Zoroastrian and Christian cultural exchange in Middle Eastern communities from the 2nd to the 6th or 7th centuries.