Board Thread:Theories and Speculation/@comment-3001903-20160325042829/@comment-734582-20160325121827

Caseather wrote: Why weren't the Tailed Beasts utilized during "An era where power was everything." It seems that the Tailed Beasts were completely absent from that time period. There were no reliable means to control their power.

Hashirama was the first to tame and spread the beasts. Only a village has the necessary resources to control them. The Hidden Sand managed to seal Shukaku in a teapot, while Uzumaki sealing techniques likely led to the age of Jinchuriki.

So during Warring States the Biju simply roamed the earth and when they came in contact with humans, destruction ensued (Hence why they were called a force of nature early in Naruto)