The Sana originates from four springs gushing into a karst plateau of the Bosanska Krajina, near the villages of Pečka and Mrkonjić Grad, not far from the city of Šipovo. After a length of about 1.5 km , these streams meet to form the Sana, which then pass near the town of Ključ in a south-north direction that the river maintains for many kilometers. The river later combines with the waters of its main tributary, the Sanica River.