Isn't Rastakhan titular king of all trolls?
Interesting. Horde has some interesting procreation techiques that can reform three ships worth of orcs into a huge nation.The Darkspear have grown since allying with the Horde. This is said during Vol'jin's novel as Khal'ak (A Zandalari envoy) notes how the Darkspear thrive and grow while all other tribes are dwindling, even offering Vol'jin to make the Darkspear the Zandalari Empire's first tribe above all others
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It makes sense, as at this time the first halfbreed generation would be ready to fight.