Nuragic Culture 1800 - 250 BC

Proto- Nuraghe Albucciu near Arzachena, Province Olbia-Tempio, Sardinia, Italy. These are just platforms with internal stairways to the top.https://commons.wikimedia.org/wiki/File:Nuraghe-albucciu-2.jpg

Bonnanaro Culture 1800-1600 BCE

(February 24, 2024) This culture is the earliest phase of the Nuragic culture on Sardinia and it is found over the whole island. The earliest Nuraghe were built at this time. They consisted of tall stone towers with an internal stairway to a top platform. So they were only good for signaling the neighbors and a few days defense with bows. They are found along the coast and along the rivers which were the main raiding paths then just as they were during the Viking era.

Consequently, these are called proto-nuraghe.

 This culture divided into 2 sub-phases:

The Bonnanaro grave typologies include the domus de janas, caves, cists, and barrows (gallery grave, long dolmen) so they were a continuation of the previous culture. So only the material culture changed and not the religious culture.

Reference

https://en.wikipedia.org/wiki/Bonnanaro_culture

Nuragic Corona Moltana Sites 1800-1650 BCE

Notice these proto-nuraghe are found along the coasts and rivers, the paths the seaborne raiders would have taken. Many more smaller ones likely existed.

References

Prehistoric Sardinia. History, materials and monuments at Sardegna Digital Library. Online at: https://www.sardegnadigitallibrary.it/detail/6499b97be487374c8f80390c

via

https://commons.wikimedia.org/wiki/File:Carta_di_distribuzione_dei_siti_della_facies_Corona_Moltana_di_Bonnanaro.jpg

Nuragic Sant'Iroxi Sites 1650-1600

Drone view of Nuraghe La Prisgiona showing this one is a a castle like estate having rooms for worker and retainers. The tower would have been used for a last ditch defense, signaling, and observation. Such networked tower estates would have been good defense against seaborne raiders.
From Google maps.

Later Nuragic Culture

Various sources claim about 7000 Nuraghes exist in Sardinia.