The once-powerful Alsuran Empire was a civilization in the Delta Quadrant near the Krenim Imperium wiped out by Annorax's Krenim weapon ship.
The only evidence that they had ever existed was an example of their food, saved by Annorax aboard his ship. This dish was served at a dinner prepared for Annorax, Chakotay, and Tom Paris in 2374. (VOY: "Year of Hell, Part II")
Since so little was said of this empire, it is unclear if the Alsuran Empire was an interstellar power or it was simply a group of nations on one planet. It is also unclear if the Alsuran Empire exists in the "restored" timeline of the 24th century.
Perhaps fortunate for the Alsurans, Paris did not finish his dish.