Can you clarify your question a little bit more?
Vietnam, Korea and Japan all adopted Chinese writing scripts at some points in their history, include the way to write numeral characters. Thailand on other hand, never did.

For Vietnam, the adoption did partly come from subjugation. People who lived in the area known as modern day northern Vietnam, as far as we know, did not have a writing scripts by the time they were conquered by Chinese dynasties in 3rd century BCE. So the adoption of the Chinese writing system became most natural and persisted until 19th century when it was gradually replaced by the Latin script and Arabic number.