The Tanaro (Italian pronunciation: [ˈtaːnaro]), known as Tanarus in ancient times and Tane or Tani in piedmontese language, is a 276-kilometre (171 mi) long river in northwestern Italy. It rises in the Ligurian Alps, close to the border with France and is the most significant right-side tributary to the Po in terms of length, size of drainage basin (partly Alpine, partly Apennine) and discharge.