American dogs trace back their origins from Asia, a new study found.

Europeans' arrival in America led to widespread disease and starvation that killed many dogs. It was generally assumed that indigenous American dogs either died or mated with Europeans and formed mixed breeds. However, a new study has found that the American dogs have ancestors in Asia and that their population is well-preserved.

Dogs first came to the Western Hemisphere along with humans who migrated from Northeast Asia. Until, Columbus' arrival, humans along with their dogs remained isolated from the events in Europe and Asia.

The study, conducted by researchers from KTH Royal Institute of Technology in Stockholm, was based on genetic analysis of about 30 dog species. Researchers found that these dogs share less than 30 percent of their DNA with European dogs, showing that these dog populations were present when humans formed civilizations in the Americas.

The study also found that the smallest dog breed- the Chihuahua- is an indigenous Mexican dog.

 "Our results confirm that American dogs are a remaining part of the indigenous American culture, which underscores the importance of preserving these populations," Peter Savolainen, a researcher in evolutionary genetics at KTH Royal Institute of Technology in Stockholm said in a press release.

In the study, researchers looked at the mitochondria of Asian and European dogs, remains of ancient dogs and dogs found in America such as Chihuahuas, Peruvian hairless dogs and Arctic sled dogs.

The scientists found a direct link between ancient American dogs and modern breeds. The mitochondrial DNA is inherited from the mother and remains relatively unmodified over many generations. Analyzing the mitochondrial DNA can give information about ancient maternal ancestry, npr.org reported.

"It was especially exciting to find that the Mexican breed, Chihuahua, shared a DNA type uniquely with Mexican pre-Columbian samples," Savolainen said. "This gives conclusive evidence for the Mexican ancestry of the Chihuahua."

Genetic analysis of stray dogs in the U.S. and South America showed that they share genetic make-up of the ancient indigenous American dog. The research team said that Carolina Dog, a stray dog found in the U.S. may have originated from ancient American dogs.