One day a king in India wanted his son Siddhartha to not see the suffering outside of palace. He want his son to have a good life, so made his son stay in the palace.
One day Siddhartha went outside of the palace. When he was outside he saw sick, old, and dead people. He felt sorry for them.
Siddartha went out in where there was a lot of grass to meditate. Then he understand the people he saw and that is how he becomes the Buddha. This is when he reached the state of nirvana.
It spread throughout China to South East Asia.
It spreaded because an India king named Ashoka did Buddhism and he sent monks and nuns to spread the pratice world wide.
Buddhism taught that the Middle Way was moderation, the 4 Noble Truths was truth of suffering and the Eightfold Path was doing the right thing. Buddhism and Hinduism connected because they believed in Karma, Dharma, and reincarnation.