This village appears in Otto II's diploma as a mercantile village under the jurisdiction of Luni bishops. Federico I then strengthened the commercial vocation of the village. Santo Stefano's strategic position attracted the attention of many conquerors, while the village itself was quite riotous against its masters, for example revolting against Genoa when this latter rose the price of salt. In 1814, the Vienna Congress handed over Santo Stefano to the Regno di Sardegna, as a part of Ligury and Sarzana territory.