The name of the village appears for the first time in a document of 937 as Garniano, perhaps derived from the Latin stem Garenius. Passages of the Roman historian Titus Livius and inscriptions on headstones testify to the presence of Etruscans, Celts, Cenomani and Romans.
Lorenzo Fiorini, Domenico Pattuccelli and Tommaso Chiaromonte, volunteers in the southern army of Giuseppe Garibaldi during the military campaign of 1860
Alexander Bettoni Cazzago, soldier, partisan and horseman. Won the Siena Square dressage competition in 1942. As colonel of the Third Regiment of the Savoy Cavalry in 1942 he led charges in the Russian campaign that are among the last uses of cavalry in modern warfare.