I recently came across this sentence with the following translation:
Sämtlich waren sie dem Staat eigen. – They all belonged to the State.
So far, I have not seen such a construction with eigen and guess that the general construction is etwas jdm/etw(dativ) eigen sein. Is this correct?
Source: Hammer’s German Grammar and Usage 3rd Edition page 114, Martin Durrell, Arnold 1996.