Board Thread:Theories and Speculation/@comment-33241126-20171003101407/@comment-33156027-20171004124001

Bijuu aren't living beings like people or normal animals. They are living clusters of chakra. Yin Kurama wasn't dead. He was consumed by the reaper with Minato and when Orochimaru cutted shinigami's stomach he was released and incarnate in Minato's reanimated body because he was still his jinchuriki (the soul of bijuu and the soul of jinchuriki are connected).