Re-occurring nightmare

could this by the slightest chance be a demons "play ground" that was sealed and the demon attached to an anchor such as the tree. If this is indeed a demons place then I would suggest making more note of what you do in the dream and if it's tied to the tree then I would suggest not breaking the way the reigns are tied, if you couldn't handle a demon but if your up to it then I say try to release it without touching the horse itself although if this isnt a demon then you may be in a traped spirits world which in turn if you help the spirit it would more than likely reward you on the spirit plane somehow and may you please explain the way the fields looked around you and if there was anything that seened a bit unusual for the area that you where in along with how it felt when you died like for example it felt peacful or it felt like allot of tingles such as electricity any info would be helpful into figuring out if this was a dream or a spiritual visitation
Note: all of the above is just a theory due to my ecnounters witht spirits and I would like to help others in order for them to avoid being trapped the way I was.

Blessed Be