Why was forced labor in each region different?

Which regions?

Explanation:

You have to tell us which regions.

Because they all harvest and require different needs. Slaves were important to the colonial economy because it helped them get a lot of work done.

Explanation:

polisit can also mean a body of citizens. in modern historiography, polis is normally used to indicate the ancient greek city-states, like classical athens and its contemporaries, and thus is often translated as "city-state". the body of citizens came to be the most important meaning of the term polis in ancient greece.