I could not find any markings denoting which country these could have originated from but my guess is Germany due to the same style as the World War 2 variants. 

Otherwise, these could connect to just about as many other shelter quarters you'd like, depending on the size of your desired shelter. If you are a lone wolf and don't need to connect yours to another, these can be used as a poncho. 
There is a slit in the middle, but they seem quite small. If you have a large head, you might have difficulties putting it through. 
 
These appear to be in great shape. But since these are used surplus, please expect small stains, holes, tears, markings, and/or fraying. Otherwise, they are ready to be used.