There's some subtext to the presentation as well revolving around W'Kabi of the Border Tribe. The dialogue only hints at this sub-story
One day, as Wakanda prospered, a weapons trafficker named Ulysses Klaue managed to infiltrate Wakanda and steal a quarter-ton of vibranium. To facilitate his escape, Klaue triggered a bomb at the border, killing several members of the Border Tribe, including W'Kabi's parents. Unable to recover from this trauma, he began to devote a deep hatred to Klaue and swore to hunt him down until his death.
Klaue wasn't just some criminal at this point. He was more or less the Wakandan version of Osama Bin Laden, the man who plotted the Sept 11, 2001 attacks. W'Kabi (and a lot of others) wanted him dealt with, something that King T'Chaka (T'Challa's father, who was apparently more isolationist) was unwilling to handle (all quotes from this transcript)
T'CHALLA: Klaue has escaped our pursuits for almost 30 years. Not capturing him was perhaps my father's greatest regret. I wish to bring Klaue back here to stand trial.
W'KABI: My parents were killed when he attacked. Not a day goes by when I do not think about what Klaue took from us, from me.
Things do not sit well with him when T'Challa returns empty-handed
W'KABI: What's going on, brother? Where is Klaue?
T'CHALLA: He's not here.
T'Challa's eyes lower regretfully
T'CHALLA: He slipped through our hands.
W' KABI: Slipped? For 30 years your father was in power and did nothing. With you I thought it would be different. But it's more of the same.
Manwhile, Erik Killmonger became highly skilled at taking down governments
ROSS: Now these guys [referring to Killmonger, et. al.] are serious. They will drop off the grid so they can commit assassinations and take down governments.
Killmonger knew a great deal about Wakanda's politics, undoubtedly from his father, Prince N'Jobu. Klaue's attack on Wakanda would have been known to N'Jobu (30 years from 2016 would put this attack somewhere around 1986, well before N'Jobu's death in 1992) and it's very possible Killmonger was told of it. As such, he would know that not only would it get him immediate respect from the Border Tribe (most of all W'Kabi), but also gain him their political allegiance as well (which it did).