The Sajó ( , Hungarian) or Slaná (Slovak) is a river in Slovakia and Hungary.
Its length is 229 km, of which 110 km is in Slovakia. Its source is in the Stolica Mountains range of the Slovak Ore Mountains. It flows through the Slovak town Roà ¾à Âava and the Hungarian city Miskolc. In Hungary, Sajó flows through the county of Borsod-Abaúj-Zemplén. It flows into the River Tisza near Tiszaújváros. Its main tributaries are the Bodva and the Hornád. It is also known for the Battle of the Sajó River, near Muhi (then Mohi), from 11 April 1241 between the Mongol Empire and the Kingdom of Hungary.
Catchment area of the Sajó river by country:
Important hydrological stations along the Sajó river:
Complete list of streams (slovak <nowiki/>'potok'<nowiki/>; Hungarian patak<nowiki/>') and rivers flowing into the Sajó (from the estuary upwards):
The origin of the name is the subject of scholarly discussions. Hungarian linguists and historians suggested the derivation from the Hungarian sojó, só folyó (salt water, river) already in the 19th century. Newer theories associate the name with sió referring to fast streams. According to Slovak linguists, the name is pre-Hungarian (Slaná: salt river) and most likely not associated with the salinity but with the salt road existing already in times of Great Moravia. The supporters argue by citing numerous Slavic toponyms in the river basin and by local names related to soþ (salt) and Moravia like Moravce, Soþár, Solià ¡ÃÂe, Soþka, SoþnÃÂk, Morava (according to this interpretation the Hungarian name is a later translation).