Cultural diffusion
Stupas and Pagodas are Buddhist holy buildings.
First in Northern India, then it spread to China and southeast Asia. In some of the countries that it spread to it was adapted to local customs (mostly rituals), but the teachings are the same regardless of the local adaptations.
The last edit was super wrong. The answer is Theravada and Mahayana. Those were the two Buddhist groups that spread Buddah's ideas to Southeast Asia. Then, Buddah's idea was adopted in Ceylon and Sri Lanka. They are described as cities, not as the name of the groups that spread Siddharta's idea. That answer from the last person? He or she needs help.
Prince Shotoku helped spread Buddhism in Japan by building a grand Buddhist temple and by writing commentaries on Buddhist teachings.
Islam spread to the island of southeast Asia through traders and merchants. Many of the city states in Malaysia and west Indonesia had a strong maritime trading orientation and as a result, accommodated many Muslim merchants from Arabia, India, and the East African coast. As a result, the ideas of Islam became incorporated in those areas, supplanting the previous Buddhism. In the rest of Southeast Asia, such as Thailand, Cambodia, Laos, Burma, and Vietnam, the orientation was much more inland and river-based trade, meaning that Islam did not have the same inroads and access.
Conversion of merchants was the strategy used by Buddhist and Christian missionaries employ to spread their faith.
Prince Shotoku helped spread Buddhism in Japan by building a grand Buddhist temple and by writing commentaries on Buddhist teachings.
Throughout southeast Asia.
Hinduiasm
it spread throughout southeast and south asia
cultural diffusion
Buddhism first spread throughout India. Then it spread into China. As it spread into China it spread into Sri Lanka and then to Southeast Asia. From China it spread into Tibet, Korea and Japan. As of now Buddhism is practiced in all of the continents except Antarctica, (unless of course a Buddhist happens to be visiting). Buddhism is most prevalent in Asia and least prevalent in Africa. Buddhism is the fastest growing religion in Europe and North America. So Buddhists now are everywhere