The Klyazma (Клязьма, Klyaz'ma or Kliazma), a river in the Moscow, Nizhny Novgorod, Ivanovo and Vladimir Oblasts in Russia, forms a left tributary of the Oka. The 686 km long river's drainage basin is 42500 km2. The Klyazma usually freezes up in November and stays under the ice until mid-April, although in faster-moving stretches ice-free water occurs until the air temperature drops below -10 °C. The largest tributaries of the Klyazma include (from source to mouth): The Klyazma is navigable within 120 km from its estuary and in the area of the Klyazminskoye Reservoir. The cities of Gorokhovets, Mendeleyevo, Pavlovsky Posad, Vladimir, Kovrov, Shchyolkovo, Losino-Petrovsky, Noginsk, Orekhovo-Zuyevo, Sobinka and Vyazniki stand on the shores of the Klyazma River. The basin of the Klyazma formed the center of the Vladimir-Suzdal principality in the 12th to 14th centuries CE.