The Horde campaign don't start until after the Human and Undead campaign. So yes, she's right. They don't come in until the game is near completion.

Well, the halfway point isn't what I'd call "late" in the story, and it's certainly not "near completion" at that point. And that's not even considering the expansion.

It's nearer the end than the half way point since you get Prologue with Thrall > Human > Undead > Orc > Night Elf. Considering how long the Undead campaign is.

Regardless, you're still wrong and she's still right. They came in pretty late in Warcraft III.

And we're not considering the expansion because the expansion pack because it's definitely more like a sequel than just a mere addon.

The same way Tides of Darkness and Beyond the Dark Portal Warcraft II books are separate novels.

The point she made was that Tauren are relatively new in terms of Lore, and history with the Horde. They showed up halway through the game on the third game. Orc and Human lore had been around 10 years previous to that, and elves, trolls, goblins, and undead all existed in lore as early as Warcraft 2. Tauren were completely new in Warcraft 3; everything else had been there before, even if it was in a different form.