Learn Dutch: Hoe wist de wolf ongezien het territorium te betreden? - How did the wolf manage to enter the territory unseen?

This sentence uses the weten te + infinitive structure. While weten alone means 'to know', combining it with te and another verb (here, te betreden) changes the meaning to 'managing to' or 'succeeding in' doing that action.

Could I use binnen te gaan instead of te betreden?

Yes, het territorium binnen te gaan also works. However, betreden (literally to tread upon or step into) is an excellent B2-level verb often used for entering land, restricted areas, or habitats, making it a very natural choice here.

Is ongezien an adjective or an adverb in this sentence?

It acts as an adverb describing how the wolf entered the territory. Because it is an adverb, it takes the base form ongezien and does not get an -e ending, which it might need if it were an adjective placed directly in front of a noun.

Why is te betreden placed at the very end of the sentence?

This follows the standard Dutch verb bracket. The conjugated verb wist takes the second position in this question, pushing the rest of the verbal block (te betreden) to the very end of the clause, after the direct object het territorium.