"They come to you as friends, and when they've won your trust they declare you subjects of the Annari Empire."

The Annari Empire was an empire governed by the Annari. According to the Kraylor, they expanded their empire by approaching other species as friends, but once they had gained their trust, they annexed them into their empire. They were at war with the Kraylor since at least 2374, when they erected a blockade of the Kraylor homeworld that would prove to be nearly impossible to pass for the following three years. Ultimately the Kraylor developed cloaking technology on a secret off-world base by 2377, breaking the blockade.

Also in 2377, the Federation starship USS Voyager made first contact with the Annari Empire while it had landed for a major maintenance overhaul on an uninhabited planet in Annari space. Though the Annari initially were amenable to their presence and even planning to trade with Voyager, they insisted that Voyager leave their space immediately when they discovered that Ensign Harry Kim and Seven of Nine had aided the Kraylor. (VOY: "Nightingale")

Though never stated, having an established method of conquering would suggest that the Empire apart from the Annari also consisted of several subject species.
The planet Voyager landed on must have been very close to the border, most likely less than a light week, as Voyager was able to be escorted outside Annari space on impulse speed in what seems like a relatively short period.