Syas River is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 in the Novgorod

Novgorod Oblast

Novgorod Oblast is a federal subject of Russia , located between Moscow and Saint Petersburg. Its administrative center is the city of Veliky Novgorod. Some of the oldest Russian cities, including Veliky Novgorod and Staraya Russa, are located there...

 and Leningrad Oblast

Leningrad Oblast

Leningrad Oblast is a federal subject of Russia . It was established on August 1, 1927, although it was not until 1946 that the oblast's borders had been mostly settled in their present position...

s of Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

. The Syas River flows from Valdai Hills

Valdai Hills

The Valdai Hills are an upland region in north-west of central Russia running north-south, about midway between Saint Petersburg and Moscow, spanning the Novgorod, Tver, Pskov, and Smolensk Oblasts....

 north into Lake Ladoga

Lake Ladoga

Lake Ladoga is a freshwater lake located in the Republic of Karelia and Leningrad Oblast in northwestern Russia, not far from Saint Petersburg. It is the largest lake in Europe, and the 14th largest lake by area in the world.-Geography:...

. A town of Syasstroy

Syasstroy

Syasstroy is a town in Volkhovsky District of Leningrad Oblast, Russia, located near the mouth of the Syas River, at the confluence of the Valdonka and the Syas Rivers, close to Lake Ladoga, east of St. Petersburg. Population:...

 is located at its mouth. The largest tributary is Tikhvinka River. Syas freezes up in November (sometimes in December or even January) and stays under the ice until April.

During the late Vendel Age and early Viking Age

Viking Age

Viking Age is the term for the period in European history, especially Northern European and Scandinavian history, spanning the late 8th to 11th centuries. Scandinavian Vikings explored Europe by its oceans and rivers through trade and warfare. The Vikings also reached Iceland, Greenland,...

, the Syas River was popular as an alternative route to the Volkhov

Volkhov

Volkhov is an industrial town in Leningrad Oblast, Russia, situated east of St. Petersburg, on the Volkhov River. Population: -History:...

 for penetrating from the Baltic Sea

Baltic Sea

The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

 through portage

Portage

Portage or portaging refers to the practice of carrying watercraft or cargo over land to avoid river obstacles, or between two bodies of water. A place where this carrying occurs is also called a portage; a person doing the carrying is called a porter.The English word portage is derived from the...

s to the Volga River

Volga River

The Volga is the largest river in Europe in terms of length, discharge, and watershed. It flows through central Russia, and is widely viewed as the national river of Russia. Out of the twenty largest cities of Russia, eleven, including the capital Moscow, are situated in the Volga's drainage...

. A fortress of Alaborg

Alaborg

Álaborg or Áluborg is the name of a Varangian fort mentioned in the Norse sagas about Halfdan Eysteinsson and Hrolf Ganger. The first saga indicates that it was possible to sail from Aldeigjuborg to Alaborg northward by sea, but a more rapid and practicable way was by land eastward...

 was built by the Vikings to guard the approaches to the Syas rapids. The route had declined by the 10th century.