They are spartiates - property owners and citizens of Sparta. They existed in small numbers (400 - 1000 ?) around the time of our game (with only about 100 as large scale property owners at the start possibly), and then reforms in the 240's opened it up a lot more to other Lakonians and greatly increased their numbers (but diluted them also in some senses). These men had more than likely also served as mercenaries (often led by their own king) in places like Egypt and South Italy and Crete.