It depends on what the original Pali term was for ‘’Tranquil Mind ‘’.
Here are the 31 Planes of Existence, and the Devas live in The Fine Material World (rupa-loka).http://www.accesstoinsight.org/ptf/dham ... .html#rupa http://www.accesstoinsight.org/ptf/dham ... /loka.html
As Thanissaro Bhikkhu says: ‘’ It is pointless to debate whether these realms are real or simply fanciful metaphors that describe the various mind-states we might experience in this lifetime. The real message of this cosmology is this: unless we take steps to break free of the iron grip of kamma, we are doomed to wander aimlessly from one state to another, with true peace and satisfaction forever out of reach. The Buddha's revolutionary discovery came in finding that there is a way to break free: the Noble Eightfold Path, which equips us with precisely the tools we need to escape from this wearisome wandering, once and for all, to a true and unshakeable freedom.’’