Hippeis

Hippeis (Ancient Greek: ἱππεῖς, singular ἱππεύς, hippeus) is a Greek term for cavalry. In ancient Athenian society, after the political reforms of Solon, the hippeus was the second highest of the four social classes. It was composed of men who had at least 300 medimnoi (or their equivalent) as yearly income. This would give them the ability to purchase and maintain a war horse during their service to the state.

Its counterparts were the Roman Equestrians and medieval knights.

In Sparta, the hippeus was the royal guard of honour. It consisted of 300 Spartan youths under the age of thirty. These soldiers were initially mounted, but later they would serve as heavily armed foot soldiers. The Athenian cavalry was formed after the Greco-Persian War in the 5th century BC; it originally consisted of 300 men and then increased to 1,200 men following Athens' Golden Age. This included 200 mounted bowmen (hippotoxōtœ) and 1,000 Athenian citizens. The hippeus continued drilling in times of peace. They also took part in processions at public festivals. They were commanded by two hipparchi, who superintended the levy. Subordinated to each hipparch were five phylarchi, who each commanded a phyla. Both sets of officers were drawn from the two highest classes. It was the duty of the boule (council) to see that the cavalry was in good condition and to examine new members with respect to their equipment and eligibility.

The number of horsemen dispatched was determined by the decree of the popular assembly. Every horseman received equipment money on joining and a subsidy for keeping a groom and two horses; this grew to be an annual grant from the state, amounting to forty talents, but regular pay was only given in the field.

...
Wikipedia