Unemployment, in the way that it is currently define, is a modern scourge. Almost by definition if someone earns his (or her) subsistence by being a farmer, it is hard to be unemployed.
The modern world, that assumes large population in cities, and mostly belonging to the services sectors, depends on demand, either by customers, or by the government.
Alas that demand is not always present, and thus unemployment increases.
Unemployment varies widely in the world, and even within countries. Also unemployment is notoriously hard to measure, but there are some European countries that suffer from high levels of unemployment.
The fact that some European countries have high levels of unemployment, and other European countries do not, make the united Euro currency harder to manage.