Hystaspes' birth year can be deduced from the fact that his son Darius was born c.550 BCE; Hystaspes must have been some twenty years old when he became father, so we can assume that he was born before c.570 BCE. According to the Greek researcher Herodotus, he had several other sons (Artabanus, Artaphernes and Artanes) and at least two daughters, who were married to Gobryas and Otanes, Persian noblemen.
Herodotus tells us that Hystaspes was in the Persian army during the last war of Cyrus the Great, which took place in the last months of 530 and was fought against the Massagetes. After Cyrus' death in December, he was succeeded by his son Cambyses, who may have appointed Hystaspes as satrap (governor) of Parthia. It was in this quality that Hystaspes played an important role during the civil war which broke out in 522. Our main source about the events are Herodotus' Histories and the Behistun inscription.
In March 522, a Magian named Gaumâta seized power, saying that he was Cambyses' brother Smerdis, who had secretly been killed. Immediately, Cambyses advanced to the usurper, but he died of natural causes; the false Smerdis was able to rule for several months. However, Hystaspes' son Darius, together with Otanes, Gobryas and four other noblemen, killed the usurper (29 September 522). Darius became king and had to face a serious crisis: nearly all provinces of the Achaemenid empire revolted. The new king spent the autumn and winter in Babylonia, fighting against the rebel king of Babylon, Nidintu-Bêl, and reorganizing the Persian armies.
The most important rebellion was that of the Medes, whose leader was king Phraortes. In December, he seized the important city of Ecbatana, where a Persian garrison must have surrendered. The rebellion spread to the north to Armenia, to the west to Assyria and to the east to Sagartia and Parthia. Perhaps it could have spread further to the east, where the inhabitants of Margiana were revolting, but satrap Hystaspes stood his ground in Parthia. During the winter, the Parthians were preparing an assault on Hystaspes' garrison, as we can read in the Behistun inscription:
King Darius says: The Parthians and Hyrcanians revolted from me, and they declared themselves on the side of Phraortes. My father Hystaspes was in Parthia; and the people forsook him; they became rebellious. Then Hystaspes marched forth with the troops which had remained faithful. At a city in Parthia called Višpauzâtiš he fought a battle with the Parthians. Ahuramazda brought me help; by the grace of Ahuramazda my army utterly defeated that rebel host. On the second day of the month Viyaxana [8 March 521] the battle was fought by them.
When the bodies and prisoners were counted, it turned out that 6,346 Parthians were killed and 4,346 taken captive. However, it is questionable whether Hystaspes did indeed 'utterly defeat' the soldiers of Phraortes, because more fighting was to follow. But the spread of the revolt was delayed and -even more important- the Parthians were prevented from aiding Phraortes in the west.
In the spring, king Darius invaded Media, and on 8 May 521 BCE, he defeated Phraortes at a place called Kunduruš [Kangavar?]. Darius took Ecbatana and Phraortes fled to Parthia, hoping to find support. However, he was caught at Rhagae; Darius mutilated him and had him crucified at Ecbatana. What happened next, we can read in the Behistun inscription:
King Darius says: Then did I send a Persian army unto Hystaspes from Ragae. When that army reached Hystaspes, he marched forth with the host. At a city in Parthia called Patigrabanâ he gave battle to the rebels. Ahuramazda brought me help; by the grace of Ahuramazda Hystaspes utterly defeated that rebel host. On the first day of the month Garmapada [11 July 521] the battle was fought by them.
Patigrabanâ means 'place where goods are collected' and is perhaps identical to modern Mashad, where several trade routes came together. The battle near this trade center marked the end of the rebellion in this part of the Achaemenid empire; the satrap of Bactria, Dâdarši, mopped up the last resistance in Margiana. Not without satisfaction, Darius wrote that his father's army had killed 6,570 and captured 4,192 enemy soldiers. Darius had every reason to be grateful to Hystaspes, because Phraortes had been unable to attack him in Babylonia while the stubborn Hystaspes could attack his rear.
We do not know what happened to Hystaspes during the next years. We know for certain that Darius visited Egypt and lead an expedition to Scythia; it is possible that Hystaspes stayed in Persia as regent.
He is mentioned in the founding inscription (known as DSf) from the royal palace which Darius built at Susa after 520:
King Darius says: Ahuramazda, the greatest of the gods created me, made me king, bestowed upon me this kingdom, great, possessed of good horses, possessed of good men. By the favor of Ahuramazda my father Hystaspes and Arsames my grandfather were both living when Ahuramazda made me king in this earth.
In another inscription, which was added when the palace was finished, Hystaspes is no longer mentioned; he must have died before the building was complete. The Greek author Ctesias, who is not known for his reliability, tells a strange story about the death of Hystaspes: together with his first wife, he wanted to visit the tomb that their son Darius had ordered to be cut in the rocks at Naqš-i Rustam, but when they were hoisted up, something went wrong, and they fell to their deaths.note[Ctesias, Persica §19.] There are some indications that this incident took place in 495 BC, which means that Hystaspes reached the venerable age of more than seventy-five years.
His younger brother Pharnaces, the treasurer of Darius, seems to have died two years before.
This Hystaspes is not to be confused with his namesake Hystaspes, who is mentioned in the Avesta, although the mistake was already made in the fourth century CE.note[Ammianus Marcellinus, Roman History 23.6.32.]