Just at it says on the can. If you look at the more famous ancient cultures (i.e. Rome, Persia, Assyria, Egypt, the Meso-American Empires such as the Aztec Empire, etc. ) did in one form or another rely on slave work for agricultural and other physically demanding tasks.
My questions, hence, are whether or not there were notable empires which could make do without (a significant) slave workforce, and whether or not an ancient high culture actually could exist without the use of slavery.
From my own (limited) knowledge, it seems that only some far-eastern empires such as ancient China made very limited use of slaves, and if so, usually not in the agricultural or other manual labor-based roles that usually were reserved for slaves. Of course, then it's debatable whether serfs and slaves did have much in common or not.