 The name has a Celtic origin related with Celtic mythology and as toponym is often associated with rivers whose sand were found to be rich in gold.Orba c. 70 km course runs northwards through Piedmont from its springs in the Apennines (from the northern slopes of Monte Reixa) to its confluence with the Bormida, a right tributary of the Po.The Orba flows from a mountain region, where there are attractive villages such as Tiglieto, Molare and then it comes to Monferrato's hills.