Sangarius (Greek Σαγγάριος): river in Phrygia and Bithynia, modern Sakarya.
The Roman historian Livy tells that the source was near a mountain called Adoreus, knows that it is later joined by the Tymbrius (modern Kemer Suyu), and informs us that the double river empties itself into the Sea of Marmara. He adds that it is not a particularly big river, but that it is famous for its large quantities of fish.note[Livy, History of Rome since its Foundation 38.18.8.]
Because there are several irregular mountain ranges in western Anatolia, the course of the river is unusually curved. It initally flows to the northwest, turns to the northeast and southeast, passes south of Pessinus, turns sharply to the north, and passes along the Phrygian capital Gordium. Continuing to the west, and after a wide curve, it flows to the northnortheast and passes along Nicaea, until it reaches, some 520 kilometers from its source, the Black Sea.Livy's remark that it emptied itself into the Sea of Marmara may refer to another branch, which, in the time he is writing about (early second century BCE), reached a big lake east of the city of Nicomedia, and continued to the Gulf of İzmit. This course dried out, at some time, but was reopened by the Roman governor of Bithynia, Pliny the Younger.note[Pliny the Younger, Letter 10.41.]