It was built by the Qin Dynasty, which despite being called "the first unified China" was a fraction of the size of modern China. And was built in part to keep people who are also now Chinese, and not just Mongols, out of "China"
And it also didn't last, it was fractured whem that dynasty fell.
Other than distant genetics, they have as much in common with modern China as the Greek government does to the linage of Ptolemy.
A note that they did not resurrect the dire wolf.
Their marketing department says they did.
What they did was create a new subspecies of grey wolf that outwardly resembles a Dire wolf.
The two species diverged between 2.5 and 6 million years ago.
Six million years ago we were orangutan like apes living in trees and Chimps/Bonobos were too. 2.5 million our ancestors were Homo Habilis.