Bo Rai Cho was once a shaolin monk in Outworld. After the fall of Argus, Cho married the protectress of the realm and reached immortality.
Once he was tasked by the Elder Gods to carry his chosen one to the triumph against evil and chaos in the realm. Bo Rai Cho had chosen his son - the half-god warrior Shao Kahn and helped him to the victory and slowly Shao Kahn got the peace in all the realm. He had a daughter named Kitana from the Queen Sindel of Edenia, combined all the races of the realm and ruled them.
For centuries. peace ruled over the realm; but once Shao Kahn decided to conquer the Earthrealm. He had to win 10 tournaments to conquer it though, and Cho had decided to prevent it from happening. He couldn't participate as an Earthrealm defender, so he trained one. His apprentice Shang Tsung was to be the champion of the first tournament, but he betrayed Cho and fought against the Earthrealm. So Shao Kahn started to win all the tournaments, and Cho decided to stay away from this folly.
But after the 10th tournament, Shao Kahn ultimately failed. Earthrealm had won. But when Shao Kahn decided to invade the Earthrealm by force, Cho decided to save his granddaughter from the destruction. He lied her about her true family, making her believe that her father was last Edenian King Jerrod. But that failed when the fake Sindel killed her. Eventually Shao Kahn died, Raiden fell with him. Bo Rai Cho had no choice, but watch as the realm fell into Shang Tsung's hands.