Zhayedan

Zhayedan (Immortals) were an elite unit within the Sassanian army; they numbered at 10,000. They are possibly an orientation to the former Immortals who served the rulers of the Achaemenid Empire and possibly wore the same clothing as their predecessors. These warriors bore some of the finest and pre-eminent quality weaponry and amour of the entire Sassanian army. The Zhayedan were led by a commander bearing the title of "Varthagh-Nighan Khvadhay."

Appearances in battles
The Zhayedan were a form of cataphracts, a type of heavy cavalry shock troops. Although elites, they do not have much role in the wars involving Rome, as they were kept as reserves alongside the generals (Spah). When used, they would inflict high casualties on the enemy. Kaveh Farrokh writes in Shadows in the Desert: Ancient Persia at War that they were used often against the Arabs in the 7th century. Their appearances include the Battle of Dara, the Battle of the Bridge, and the Battle of al-Qādisiyyah.

Weapons
The immortals were equipped with some of the finest weapons of their day, including spear, sword, mace, dagger, and cane bow. They wore heavy scale or mail armor and heavy steel breastplates. According to some historians and scholars, they had golden chains and bracelets, possibly a sign of their wealth or high rank in the Sassanian army. Their helmets, of the Spangenhelm type, would have been adapted throughout the Sassanid Persian.

"But no sooner had the first light of day appeared, than the glittering coats of mail, girt with bands of steel, and the gleaming cuirasses, seen from afar, showed that the king's forces were at hand."

The immortals are said to have used the tough and powerful Nisean horse, native to the Zagros Mountains of western Iran

In popular culture

 * In the award winning strategy game Rome Total War: Barbarian Invasion the Sassanids can use immortals, they are known as "Clibanarii Immortals" and are the elite general bodyguard unit.