What historical factor severely restricted the potential speed of global breed proliferation after introduction to the West?

Answer

A small foundational population of imported individuals

The slow introduction meant that only a few foundational dogs were brought to the West, creating a bottleneck where subsequent global populations derive from this very limited genetic base.

What historical factor severely restricted the potential speed of global breed proliferation after introduction to the West?
rarityDogbreedTibetan SpanielCompanion animal