Prior to the Lunar Occupation, the Sartarite army was primarily foot militia led by mounted noblemen called thanes. The army was augmented by warrior societies, mercenaries, and various allied troops (such as Grazelanders, Pol-Joni, and Sun Dome Templars). Sartar’s military after the Liberation was a motley conglomeration of causes, defying neat and easy categorization and organization. During Prince Kallyr’s short reign, the Sartarite military consisted of her friends and companions, her personal followers, her tribe (the Kheldon), and whatever city and tribal militia would follow her to battle. During the Interregnum (1626-1627), central authority in Sartar disintegrated, and the Sartarite army was reduced to feuding tribal mobs. Upon his acclamation as Prince in 1627, Argrath concentrated upon strengthening his internal position, and above all, his army. Building on his own personal cavalry forces he raised in Prax, he made his army the greatest source of wealth, honor, and power in the principality, and quickly transformed the Sartarite army to become a uniquely flexible and effective force.
Among the Sartarites, all free men and women are expected to follow their chief in times of war and danger. In most clans, only the chief, thanes, and their bodyguards are professional warriors; most of the militia are farmers and herders. Service is typically owed to the clan chieftain, who in turn owes it to the tribal king, and on to the Prince. Each Fire Season, the local militias muster at a tribal or even city level. Members participate in athletic competitions and mock sparring contests to learn how to fight, and to strengthen them.During the Lunar Occupation and Sartarite Rebellions, the Sartarite militia were primarily light infantry skirmishers. They are lightly armored, typically with a composite or open helm and a quilted linen hauberk, and fight with sword and javelins. They are led by their clan chiefs and thanes but follow their tribal kings into war.
The Sartarite cavalry was formed in imitation of the sun-worshipping horsemen the Orlanthi encountered. These mounted and more heavily armored warriors are members of the noble castes, the only classes that could afford such things. This later led to the rise of the Orlanth Rex cult and its own mounted warrior, the “thane.” While warrior societies maintained themselves, either from plunder, tithes, or even bribes, the thane was supported by the clan or tribe itself. They became an elite class freed from the duties of other men and sworn to the fight. At the time of Prince Kallyr, thanes lead the militia or form the mounted bodyguard of the tribal kings. When Argrath becomes Prince, he gathers many thanes together to form elite cavalry regiments like the Twin Spears.
Warrior societies are maintained by War Clans and tribal War Gods, such as Orlanth Adventurous, Babeester Gor, Humakt, and Storm Bull. These are bands of full-time warriors who support themselves through raiding and looting (usually of livestock). They are experienced warriors who have often gone afield and acquired some wisdom and equipment, including mounts to get around. Warrior society members are built along cult lines (usually as members of Storm Bull, Orlanth Adventurous, or Humakt).
Individual fighters or groups of fighters are often recruited by local leaders to serve as bodyguards or professional soldiers. The guardsmen of the various Sartarite cities are mercenaries paid by the cities and mercenary companies are a common feature in Dragon Pass. Mercenary companies like the Brown Choppers and the Boldhome Axemen participated in Starbrow’s Rebellion, and the Liberation of Sartar was achieved in part with aid from numerous mercenaries like Jarandor’s Raiders, the Storm Hills Chargers, or the Hendriki Volunteers.
The Humakt and Sun Dome cultists are the best-known mercenaries in Sartar but Orlanth Adventurous mercenary companies have become quite common. Entire tribes are also known to be willing to fight for pay.
Do the tribes on the eastern side of Sartar field more cavalry due to the proximity to Prax and their comparatively open lands? It’s not it is quite so simple. I think the larger and wealthier tribes tend to have more mounted warriors, simply because they have the resources. I am sure the Runegate thanes claim they are are among the best horsemen in Sartar, which gets disputed by the Dundealos and so on.Argrath takes the best and most loyal from all the tribes and recruits them into standing cavalry regiments like the Two Spears, Eaglebrown Warlocks, and the Egglords. Membership in these units are sources of honour, status, wealth, and cult advancement. Through means like that, Argrath manages to unify his kingdom.
Out of about 175,000 humans in Sartar, less than a quarter have a sword. Which is higher than real world societies, but if anywhere on Glorantha is going to have a lot of swords it is Dragon Pass.