The tailed beasts are beings that have been split up into 9 spirits by the sage of the six paths. Some tailed beasts are Shukaku, Kurama, and Matabi. These beings each have their own different power and have a certain amount of tails. Kurama has nine tails while Shukaku have 1 tails. In the old days of the Narutoverse, the Lands seal the beasts in people to use them as weapons. These people with the tailed-beasts inside of them are called Jinchuriki.