Prince Siddhartha was prophesied to either become a great ruler or religious leader. Not wanting the 2nd option, the king kept him in a palace, raising him in isolation from the outside.
He began visiting the outside, seeing and learning about things like suffering. He many saw unhappy people and wanted to find a way to end suffering.
Karma + Darma
4 Noble Truths
Siddhartha decided to leave his royal life behind and live an ascetic life, however during this time, he decides to follow the Middle Way, a balanced way of life.
Siddhartha sat under a Bodhi tree and meditated for many days, until finally he obtained Nirvana, a state of enlightenment, and became the Buddha.
Buddha decided shared his knowledge to the world, creating Buddhism. He told about karma and dharma what determined reincarnated lives, the 4 Noble Truths a way to end the cycle of suffering, and the Eightfold Path to make one's life happy and fulfilled.
From India, Buddhism spread to China, Japan, Korea, and parts of Southeast Asia through merchants, monks, and missionaries, connecting many people.