Boris Christoff sings the Song of the Volga Boatmen (Russian title:Эй, ухнем!). This is a well-known traditional Russian song collected by Mily Balakirev, and published in his book of folk songs.
It is a genuine barge-haulers' shanty. The song, also called The Volga Burlak's Song, was inspired by Repin's famous painting, Burlaks on the Volga, depicting the suffering of the people in the depth of misery in Tsarist Russia.
(Burlaks of the Volga)
The song was popularised by Feodor Chaliapin, and has been a favourite concert piece of bass singers ever since. Glenn Miller took the song to #1 in the US charts in 1941.