No, that's Undertown. That's a different set of tunnels entirely that's part of the city. Vandal nation tunnels run all over the desert, they have whole separate cities out there under the dunes. On paper they're two separate nations with their own laws and government but in practice they're basically the same country, and there are a lot of really weird, muddy distinctions between what's the cities and what's the Vandals.
For example, the Green Belts technically belong to the city even though the Vandals are the ones that work them and the food they produce goes to feed both the city and the Vandals. Vandals can live in the city but still be counted as members of the Vandal nation. Just a weird symbiotic relationship.
Hey son, wanna' learn how ta' make witch balls?