Evanglizers
Missionarries!
Missionaries are the people who help spread a religion.
In every country or place you will find people that practice the Islamic religion, as it has widely spread thoughout the world.
First, Buddha people are generally called "Buddhists" or "followers of Buddha." They first practiced their religion in India, but it was spread by missionaries to places like China, Japan, Nepal, and all over Southeast Asia as well.
Yes, and the Muslim warriors did too....
Islam
It spread because people would bring the religion to different places, like them going on vacation to another continent so they are bringing their practices to another place and other people are learning and practicing them too.
Migration is cause of spread of religion. As people travel they bring along their religion, and the constitution does not prevent them.
A missionary
christians
Because if you're not excited about it, it isn't your religion.
People who believed in the religion and followers spread and expanded the religion as they traveled. Mostly from India to China and so on.