2.5 million years ago, a meteorite made of vibranium landed in the heart of Africa. Centuries later, five tribes colonized the area and went to war over the metal. One day, Bashenga was guided by a vision of Bast, who led him towards a plant that had mutated as a result of the metal's powers.
As time passed, the Wakandans used the metal to develop technology that was far more highly-advanced than any other in existence. To protect themselves from the chaos that was slowly consuming the rest of the world, they created a cloaking field that allowed them to hide in plain sight. Later, the world learned about existence of vibranium and many researchers attempted to find a source. However, they failed and then Wakanda became a legend. Howard Stark managed to obtain a small amount of vibranium during his trip to Africa, and used it to create Captain America's Shield.
Over time, however, N'Jobu became convinced that Wakanda's isolationist policies were doing more harm than good and that people of African descent around the world were being oppressed. He then decided that the only course of action was to initiate a global revolution. To arm his cause, he revealed his country's existence to an outsider, Ulysses Klaue, and gave him relevant information to infiltrate Wakanda.
Using N'Jobu's lead, Klaue managed to avoid all Wakandan security systems and successfully infiltrated Wakanda. Inside, he stole a quarter-ton of vibranium. Wakandans then spotted Klaue and attempted to stop him. However, Klaue triggered a bomb and explosion killed numerous Wakandan citizens, including W'Kabi's parents, what gave Klaue opportunity to escape.
For almost thirty years, Wakandans pursued Klaue around the world in order to get back stolen vibranium. Klaue successfully avoided them but once they managed to capture him. Wakandans branded scar on Klaue's neck with the symbol for 'Thief' as punishment for stealing the vibranium, however, he managed to escape them and went off the grid.