The Duchy of Genoa was the name taken by the territories of the former Republic of Genoa when they were given to the Kingdom of Sardinia by the Congress of Vienna in 1815.
Ligurian people, with their independentistic and republican traditions, never liked their new political status, and riots sometimes exploded in Genoa.
The Duchy of Genoa was finally disbanded after the perfect fusion of 1848, and it was divided between the departments (later called provinces) of Genoa and Nice.
References
Duchy of Genoa Wikipedia(Text) CC BY-SA