The Ten Thousand (Ancient Greek: οἱ Μύριοι, hoi Myrioi) were a force of mercenary units, mainly Greeks, employed by Cyrus the Younger to attempt to wrest the throne of the Persian Empire from his brother, Artaxerxes II. Their march to the Battle of Cunaxa and back to Greece (401–399 BC) was recorded by Xenophon, one of their leaders, in his work Anabasis.

Between 401 and 399 BC, the Ten Thousand marched across Anatolia, fought the Battle of Cunaxa, and then marched back to Greece.

In his Anabasis, Xenophon states that the Greek heavy troops routed their opposition twice at Cunaxa at the cost of only one Greek soldier wounded. Only after the battle did they hear that Cyrus had been killed, making their victory irrelevant and the expedition a failure.

The Ten Thousand found themselves far from home with no food, no employer, and no reliable allies.

They offered to make their Persian ally Ariaeus king, but he refused on the grounds that he was not of royal blood and would not find enough support among the Persians to keep the throne.

They then offered their services to Tissaphernes, a leading satrap of Artaxerxes, but he demanded their complete surrender, which they refused. This presented Tissaphernes with a problem – a large army of heavily armed troops, which he could not defeat by frontal assault. He supplied them with food and, after a long wait, led them northwards for home.

Meanwhile he succeeded in luring away the Persian general Ariaeus and his light troops.^{[citation needed]}

The Greek senior officers accepted the invitation of Tissaphernes to a feast where they were taken prisoner, led before the king, and executed.