The nearly 800 pieces “of exceptional rarity and inestimable value” date as far back as the sixth century BC, according to the Carabinieri police force’s tutela patrimonio division in charge of protecting cultural heritage.

The finds including stelae, amphorae and other works, which came from clandestine excavations in Puglia in Italy’s southeast.

The investigation began in 2017 after a state archaeology lab in Puglia noticed in European art catalogues that decorative elements from a Daunian funerary stele belonging to the collector resembled those found within a fragment in a southern Italian museum.

That flat stone slab from Daunia – a historical region of Puglia – in the collection of the Belgian collector was missing a piece in its centre.

An official within the restoration lab noticed that the piece in the museum’s collection completed the design of a shield and a warrior on horseback that was missing on the stele.

“During the course of the search, a veritable ‘archaeological treasure’ was recovered, consisting of hundreds of Apulian figurative ceramic finds and other Daunian stelae, all illegally exported from Italy, which were then seized in Belgium,” read a statement from police in the city of Bari, Puglia.

Italy was able to repatriate the works after legal appeals by the collector were dismissed, police said.

Besides stelae, the collection includes vases painted with red figures, amphorae, black glazed ceramics, and numerous terracotta figurines. The pieces date back to between the sixth and third centuries BC.