Alsuran Empire

From Memory Alpha, the free Star Trek reference

The once-powerful Alsuran Empire was one of the many civilizations wiped out by Annorax's Krenim weapon ship. (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.