Mercenaries
Mercenaries (MURR-sinn-air-eez) are paid volunteer
soldiers: they are soldiers who are fighting as a job, not in order
to save their country or for the glory of God.
They only fight if they are paid, or for the booty they will get if
they win. Often they will change sides if the other side offers more
money.
Many ancient and medieval governments hired mercenaries to fight their wars. Greek men seem
to have been especially skilled mercenaries. We know that Greek
men fought as mercenaries for the Egyptians
and the Syrians as early
as the Late Bronze Age,
and other Greek men fought
as mercenaries for the Egyptians
against the Persians
in the 500's and 400's BC. In the 300's, Greeks
fought for the Persians, in a civil war.

Nubian mercenaries from 11th Dynasty Egypt
The Egyptians also hired many Nubian men to fight for them as mercenaries. The Persians hired Arabs.
In the 300's AD, the Romans hired many Germans as mercenary soldiers, often paying them in land and a share of the taxes (though we don't understand very well how this worked). The Visigoths and the Ostrogoths both worked as mercenaries for the Romans. In the 600's AD, some Arabs worked as mercenaries for the Romans, and others worked for their enemies the Sassanians.
Once the Arabs had founded the Islamic empire, they too hired mercenaries: the Abbasid caliphs hired the Seljuk Turks as mercenaries.
