Probably happened much longer ago than 100,000 years and more than one species of 'dog'. Why are these people so arrogant in their assessments when they do not have the complete facts.
Geneticists can literally 'count' generations by tracing common genetic anomalies found in any population. You can therefore estimate the length of time since that anomaly first appeared. It's pretty well established in humans and they have been using this information to trace pre-historic human migrations. This is probably why they are saying that there were as few as 6 "domestication events" -- they probably have distilled the genetic markers down to 6 ancestral dogs.