Let's conveniently forget the 100 years of the Yuan dynasty ruled by Mongols and the 300 years of the Quing dynasty ruled by the Manchu and pretends that the history of China is the history of the Han. Why would anyone question that? It's really hard to take the article seriously given how much it oversimplifies its premises.
The article does mention both of these facts.
> "The heartland has always been threatened by the nomadic tribes that live in the north. These tribes weren’t just small groups on sporadic raids. Some were dangerous enough to conquer and rule China: the Mongols ruled for a century, starting in the 1280s, and the Manchus for nearly 250 years, starting around 1650."
Especially considering this comes after this - "Another way to put it: China is the Han, and the only thing they care about is protecting the Han" - which it direcly contradicts.