Short answers, pulled from the story.
Sardinia is the second largest island in the Mediterranean Sea, officially the Autonomous Region of Italy. It lies 200 km west of the Italian Peninsula, 200 km north of Tunisia, and 16.45 km south of the French island of Corsica. Its capital and largest city is Cagliari.
The Nuragic civilization was an indigenous culture that flourished on Sardinia from the 18th century BC to as late as the 6th century AD in some parts of the island. It is most famous for the nuraghe, round tower-fortresses of which roughly 7,000 survive today. Nuragic people traded copper and lead across the Mediterranean, producing bronze statuettes and the limestone statues of Mont'e Prama.
Eleanor of Arborea was a Female Judge, or judikessa, of the Judicate of Arborea in the 14th century. She amended and updated the Carta de Logu, a legal code written in Sardinian that included the right of women to refuse marriage and to own property, making it one of the most advanced civil codes in 14th-century Europe. Her resistance to Aragonese rule helped the Arborea Judicate occupy nearly all of Sardinia until the Battle of Sanluri in 1409.
Aragonese-Spanish rule over Sardinia lasted approximately 400 years, from 1323 to 1708. Its legacy includes the Catalan language still spoken in the northwestern city of Alghero, Spanish-derived customs visible in the folklore parades of Saint Efisio on the 1st of May in Cagliari and the Redeemer on the 28th of August in Nuoro, and the introduction of feudalism at a time when much of Europe was already abandoning it.
The Brigata Sassari, the first and only regional military unit in Italian history, fought in the First World War with Sardinian soldiers exclusively. The brigade earned four Gold Medals of Military Valor. Sardinia lost 138 casualties per 1,000 soldiers, compared to the Italian national average of 100, making it the Italian region with the heaviest proportional losses on the front.
Italian is the dominant official language, but Sardinian and the Algherese dialect of Catalan are recognized by both regional and national law as two of Italy's twelve official linguistic minorities. Regional law also protects other minority languages including the Corsican-influenced Sassarese and Gallurese and Tabarchino Ligurian. These languages were formally recognized alongside Italian in 1999.