In the quelling of these rebellions the powerful army machine built up by Darius was further strengthened. The core of the army was formed by the Persians themselves, for if they no longer paid tribute, they did pay the blood tax. At the head, under the immediate leadership of Hydarnes, son of Hydarnes, the hazarapat or commander-in-chief, was the famous bodyguard, the Immortals, who received their name because their number was never permitted to fall below ten thousand a substitute being always ready when one fell sick or was killed. Not only were they gorgeously clad in gold-decked raiment, but on the march they were permitted to take with them their concubines and servants on wagons, while special food was brought on camels and other baggage animals.

The Ten Thousand Immortals included detachments of Medes and Elamites as well as of Persians. Colored glazed bricks at Susa enliven the picture of the Elamites. Some are swarthy, almost black; others have a lighter complexion; but all are armed and clothed alike. The head is bare, with the hair held down tightly by a greenish twisted rope fillet; the short beard is curled, as is the bun at the neck; their junction is noted by a gold earring. Each soldier stands stiffly; both hands, adorned with big drooping gold bracelets, firmly grasp a spear of cornel wood whose silver blade and silver pomegranate set hard on the toe prove that they are members of the Ten Thousand. Over the left arm is the uncased bow, and over the left shoulder is the quiver. An elaborate robe covers the whole body from neck to wrists ankles, leaving only a glimpse of bare flesh above soft leather shoes which are buttoned or laced and which have high projecting tongue.

It is in the quivers, robes, and shoes that exact symmetry is forgotten and textile design and color run riot. Bits of leather, cut out in form of crescents, decorate the quiver; they may be pale yellow or pale blue on browns of differing shades, or brown on a white ground. The whole quiver may be of the same design and color save for a row strip of alternating triangles - brown and white or blue and white - at the ring from which hang down colored strings and tassels. The shoes may be yellow or blue. Sometimes the robes are a plain yelow or very light purple; if so, a rich, velvety brown cape, with an edging of green decorated with rows of white circles, is draped over the breast and under the arm to cover the hip. More elaborate robes are studded with ornaments: white or yellow stars on blue or dark-brown circles, or large, closely placed squares quartered or halved by brown lines, are sewed on the yellow or white cloth.

We must imagine similar colors for the Persian and Median Immortals at Persepolis. Here the soldiers who guard the inscriptions, climb up the staircases, line up for the nobles who visit their lord, or stand at attention while reviewed by the monarch all wear headgear, either the fluted hat of felt or the nodding felt cap. According to their ancestry, their dress is the Persian robe or the Median jacket and trousers. They may be armed only with the spear or the bow and quiver; both may be combined, and the bow case may be added. Among them are to be found the One Thousand who gave their name to the hazarapat, for these are distinguished from the remainder of the Ten Thousand by carrying pomegranates of gold.