The name Selenge comes from Mongolian seleh, which means "to swim". '
Selenga' is the russified version of the same.

An alternate source believes the name originated with the Evenki word sele ("iron") to which the possessive nge suffix was added.

The Selenge Province of Mongolia is named after the river.
The name Selenge comes from Mongolian seleh, which means "to swim". 'Selenga' is the russified version of the same.
An alternate source believes the name originated with the Evenki word sele ("iron") to which the possessive nge suffix was added. 
The Selenge Province of Mongolia is named after the river.
Selenga