As the Alliance marched toward Stormheim and its warriors stirred up trouble in the Hall of Valor, the Horde expeditionary force quietly went about its business, ignoring everything beyond their immediate task. They first made a brief stop on the island where the Tomb of Sargeras stood, then set sail again toward Highmountain. Naturally, they were going to visit the Tauren's relatives and make contact with the primitive Highmountain Tauren who had lived there for generations.
Highmountain had also been Deathwing's lair ten thousand years ago. Back then, Krasus and Rhonin had infiltrated Neltharion's den from here and stolen the Dragon Soul hidden within. They had then encountered the young Boss Hu, who had likewise followed the mental waves of the Old Gods to this place. Back then, Boss Hu had still been an unhatched, tender young hatchling. Time flew, and now he was a greasy old rogue. Ah, how things had changed.
Ahem, back to the point. As mentioned before, the Highmountain region was, strictly speaking, the birthplace of the Tauren race. The Tauren now living on the Kalimdor Continent were migrants of the new era following the War of the Ancients. After all, The Great Sundering had come after that war, and the Tauren brothers who had gone to assist in the fighting could no longer return home. They could only find somewhere new to settle.
Therefore, by making use of this familial connection, the Horde had a good chance of bringing the Highmountain Tauren into the fold and having them help build the Horde together.
And things developed exactly as they had expected. In Thunder Totem Highlands, the largest city of the Highmountain Tauren, the Horde expeditionary force received a warm welcome.
The honest and straightforward Highmountain Tauren were exceptionally enthusiastic toward these distant relatives from the