Science Magazine explains, through a really informative animated video, how researchers discovered that dogs may have more than one domestication point. To proved this theory, they looked at the history of ancient dogs in Europe (Germany) and in Asia and discovered that these dogs may have been domesticated separately in each specific geographical area.
…the data suggest that humans domesticated dogs in Asia more than 14,000 years ago, and that a small subset of these animals eventually migrated west through Eurasia, probably with people. This implies that all modern dogs, as well as the Newgrange canine, can trace their ancestry back to Asia. …Archaeologists previously had found the remains of dogs in Germany that may be more than 16,000 years old, suggesting that dogs had already been domesticated in Europe by the time the Asian canines got there. Some of today’s dogs may carry genetic traces of that early domestication—but it’s hard to find, in part because scientists are still trying to recover DNA from those ancient German dogs.