For the medical purposes
The famous Greek Herodotus, the «father of history», as it is called, wrote that the residents of the ancient steppes «always had in their settlements of the hut with the ever-burning fire. When the stones ðàñêàëÿëèñü, they poured water, sprinkled hemp seed and the hot couples washed his balls».
As has already been mentioned, steam room appeared in the East Slavic myths. It is noteworthy that about old Russian steam bath is mentioned in the famous chronicle «Tale of bygone years» (945). Tells the story of the legendary journey of the Apostle Andrew from Sinop to Rome in Kiev and Novgorod. In Veliky Novgorod Andrey saw wooden baths where people, uncovering himself, poured alkaline kvass, beat their brooms and at the end of the îêàòûâàëèñü cold water. «Âèäåõ bath äðåâåíû. And îáëåþòñÿ kvass óñíèÿíûì, and âîçìóòü on CE ïðóòüå young (and) beat be themselves, and be done away with barely ñëåçóò Le live, and îáëåþòñÿ water ñòóäåííîãî...».
In the times about which reports the chronicle, the Eastern Slavs was not yet cities. So we're talking about the V - VI centuries.
And here is another interesting detail. It turns out that the Pechersk monks showed keen interest in ancient Greek medicine. Having heard about the benefits of a steam bath, they behaved with them for medicinal purposes. Not by accident in the Charter of the Grand Prince of Vladimir (966) the baths were called institutions for íåìîãóùèõ. In the year 1091 Pereyaslavl Bishop Ephraim began to have baths, which were a kind of clinics, perhaps, the first in Russia.
About the bath we can read and in the Chronicles of the X-XIII centuries. It is called: ìîâü, ìîâíÿ, ìîâíèöà, soap, dish soap, âëàçíÿ or just steam room. In the contract between Rus and Byzantium (907 g.) Rusichi guaranteed them the right to arrival in Constantinople to use the bath: «And Yes they do them ìîâü åëèêî want.»
...Built not only wooden baths, but also of stone. So, in one of the Chronicles mention that the first stone bath is built in Pereslavl in 1090.
In the novel the wonderful Soviet writer and historian Vasily Yan «Princess», drawing a struggle of the Russian people for their independence, there is such episode.
...Winter of the year 1237. The grandson of Genghis Khan Batu-Khan äîáðàëñÿÿ with his cavalry to Moscow. His attention was attracted by log cabins near the river, out of which poured thick steam. People rushed headlong rushing out from thence, rushed to the ice hole and immersed.
Batu-Khan pointed out with a whip in the log: «What do these madmen?» «These houses are called «soap», - îáúÿñííèë the interpreter. - There residents Ìóøêàôû (so the Mongols called Moscow) beat yourself with birch, should be washed with hot water and kvass, then bathed in the ice-hole. This is very useful. Because óðóñóòû (i.e. Russian) such strong».