Answer:
Trades and conquest.
Step-by-step explanation:
Trades and conquest were an efficient method for one region to spread the characteristics of their cultures to another region.
During trades, many merchants from different regions interacted with one another and spread their cultures in the process. The same thing happened when an empire conquered another empire. They forced the defeated empire to learn the cultures of the victors.
Through these process, cultural assimilation happen. Two or more cultures adopted each other's characteristics and merged into a new type of cultures. This process happened over and over again throughout the years and resulted in many distinct cultures able to develop over time in Asia.