Are these the Easterlings?

The helmets and shields especially gave it away for me...




From my knowledge, they were indeed iconic pieces of armour for the Easterlings, at least since their depiction on this way in the LoTR movies. This is a quote about the Rhunic armour, taken from Lord of the Rings Wikia:


"The armor of the Easterlings entering the Black Gates was made from bronze, along with the helmet; its dragon-skull-shape was made to intimidate enemies.

Their gold or brass overlayed steel lamellar armor consisted of a placard (stomach plate), gorget (heart & neck coverage), groin-plate, rerebraces (upper arm), vambraces (forearm), cuisses (thighs), and poleyns (knees). The clothing that the Men of Rhûn wore consisted of red leather gloves, black leather tall boots, burgundy long pants, a burgundy tunic with long sleeves, a burgundy headscarf, and a black facecloth . The undercut, brass helmet was worn over the headscarf, and featured cheek-and-eye guards, along with two horns from the back and a crest on the front, to remind other beings of dragons, intimidating to the enemy even before the battle began. This primitive form of psychological warfare was terrifyingly effective against the Men of Gondor and Rohan and Dale, who would oftentimes literally quake in their boots at what seemed a golden horde of Easterlings swarming from the farthest East.

During battle, these heavy infantrymen formed the core of Sauron's armies, for they were taller, stronger, better-trained, and better-equipped than the swarming Orcs that fully comprised his forces.

The Men of Rhûn wore their clan-wealth as well: gold, copper, silver, rubies, and other colorful pieces of ornament-material. Easterlings also liked wearing battle trophies, talismans of victory that could inspire them to glory and riches and power and territory/region ownership and totems of fear that would intimidate their next opponents. This psychological warfare struck terror into their enemies and gave them an even greater advantage in battle. The curved, rectangular, two-foot by three-foot Easterling shield had concave top and bottom edges and was made with brass that surrounded a dark-brown square. It was held by an iron handgrip that was behind a brass circular boss surrounded by a diamond shape that was itself enveloped by the square. It came with a dark-red leather "belt" if the Man of Rhûn was to strap the shield to the forearm for combat requiring two hands. Even archery was allowed by this big strap. One rather striking detail on Rhûnic armor was that a sun was etched into their sternum-plate, resembling a burning of a grassland like Rohan or Dale.

Weapons
The Easterlings had three principal weapons: their pike, the scimitar, and the composite bow.

The steel-bladed wooden halberd came in two sizes: the nine-foot halberd was used for porcupine formations and phalanx marches, while the five-foot one was used as a basic soldier's weapon. All halberds were spiked on the top (on the five-foot one it had a pike on the bottom too) and had downward-curving, serrated axe-blades, and below that halberds were backed by a curved spike; on the nine-foot one it was used to trip enemy horses while on the five-foot one it was used for piercing armor and deflecting if not disarming enemy blades. The axe blade featured a hole creating the curve. This was a truly versatile weapon that could be used both offensively and defensively.

The three-foot-bladed steel scimitar was carried by all troops as a secondary weapon (except in the case of Swordsmen). The curved blade was used in a downward, diagonal slashing attack and for thrusting. No matter which method of attack the Easterling chose to use with his scimitar, it was extremely effective in his hands. The scimitars were particularly suited for mounted attacks, as they were long and curved, allowing the rider to swing and hit his foes.

The Composite Bow of the Easterlings was made of multiple layers of wood and was of a recurve type. They were 4 feet long at the very most, and they were carried in holsters. The arrows had hawk feathers, and the tips were forged out of steel. Easterling cavalry archers were uniquely skilled, and while riding kept their quivers slung at their sides. They learned to stand up in the saddle and release their arrows at the moment the horse's hooves were off the ground, allowing them to shoot more accurately than Rohan's horse archers. They also have three-foot-wide rectangular shields in the movie.

The Easterlings were known for their unique type of cavalry known as kataphrakts*. These were Easterlings that mounted upon heavily armored horses and wielded a scimitar and broad shield. They were notorious for their ferocity of their attacks and the sheer amount of defensive power that these troops could summon when they were deployed side-by-side. The brass lamellar armor on the fronts of their horses allowed them to safely trample spearmen and pikemen. Rhunic composite shortbows were sometimes taken instead of shields."



Since the movies, this is the way the soldiers of Rhun were depicted im most of the media, especially videogames (my favourite example is Third Age Total War, mod for Medieval II Total War Kingdoms expansion).


The only confusing thing would be now the fpag with the serpent. It is different to the one of Harad, but the style is somehow similar. My theory would be that these guys are coming from the southern region of Rhun, maybe northern Khand (the Easterlings were not one giant empire, but a confederation of tribes covering the entire east side of the map of Middle Earth), and got some Haradrim influence. This would somehow explain why they arrived at the Black Gate from south instead of north (the place where most Easterling tribes lived).


*Interesting fact: the guys in these goldern armours are supposed to ne part of the Balcoth tribe. The Balcoth were a more warrior tribe frpm the Easterlings. Another important group would be the Wainriders, but those are described more in the style of the Mongolians, as a nation of riders, manner similar to the one of Khand.





The men of Khand (Variags) are different from the Easterlings, however, they have fought alongside each other