Siddhartha grew up very protected in his palace. He had no experience of the outside world.
Siddhartha's friend tells him about the outside world. They sneak out of the palace.
Siddhartha saw three things in the town. He saw an old man, a sick man, and a dead man. He asked his friend if these things would happen to him too. He told him yes.
Siddhartha wants to know how to get rid of suffering in life. He starts meditating with aesthetics. One day a girl offers him water and rice. He accepts it. The other people don't like it. He tells them that that is not the way to get rid of suffering.
Siddhartha was meditating under the bodhi tree when he gained enlightenment and finally understood how to get rid of suffering. He was on the middle way and he found the 8 truths. He then became the Buddha.
Buddhism was spread by merchants when they were trading. Buddhism traveled all the way to Asia.