The Marches history
In ancient times, there were only savages in the lands that now form the Marches. Dawn to the East was the earlier nation, and even then it was ruled by noble houses who set compex and self-serving tests to keep power in the hands of a favoured few. Decades before the foundation of Empire, the royalty of Dawn drove the orcs and others west. They carved out the new border territory of the Riding with glorious adventure. Stories told in Dawn tell of triumphant battle against the foul orcs. The Marcher folk tell of nobles leaving the western people to deal with the raids and the actual day-today defence of the new border.
Either way, the Riding was royal land, kept whole by yeomen's sweat, and it was yeomen from there that moved further west and cleared Upwold as a genuinely independent territory.
The Marchers say their forebears rebelled against the noble houses and replaced the ridiculous system of "tests of mettle" with simple declarations of loyalty. The way the people of Dawn tell it, Marchers are the descendants of Dawnish yeomen who failed their tests and moved to the new territory in shame. Marchers say the first Landskeepers found a wilderness and made it the richest land in the world, while the Dawnish claim that the first Landskeepers were little more than upstart craftsmen who came into possession of a little stolen magic.
In Dawn, troubadors sing of the villany of letting a person rise to status by simply setting up a farm, while any Marcher will tell you anyone can rise to greatness with work. In Dawn, they believe that the test of mettle is a good measure of person's quality, while in the Marches they tell tales of noble houses setting impossible tests to keep their "lessers" in their place. Dawn hold personal glory paramount, Marchers would die nameless if duty to the household demanded. It'd be difficult to say the two nations are friends. Both sides have their legends of land stolen or rightful taxes evaded. Both nations say that any rebels in their ranks are free to try their luck in the lands of the other.
However, both nations recognise the benefits of Empire: there are greater enemies to fight.
When the first Empress came to the Marches, she had a simple story to tell. Humanity was in deadly danger. Marchers nodded at the story, and were most amused by her victory over the Lame King of Dawn in personal combat. Still more when she gifted them with his wedding gift to her - the Riding - as theirs-in-truth. She knew what they knew. The price of owning good land like theirs. The threat of barbarian orcs, and the absolute necessity of driving them into the sea. They could see that if her Empire came to be, and her war happened, the Marches, not Dawn, would be the ones to prosper. In a simple extension of the process of household fealty, the Electors of the Marches swore to send her senators, where once they'd elected one of their own as leader. The process of choosing an Emperor inherits ancient Marcher tradition.
Entry to the Empire brought some changes. Pious Marcher folk returning from pilgrimages to Highguard founded the monasteries which now dot the landscape. Friars have become an important part of most Households and few powerful Marcher households do not have one or more of these learned folk by their side. Imperial writ created the market towns, outside the control of the households. Yet the traditional beliefs that give the Marcher Folk their strength have endured every transformation brought by the Empire.
The Marches has gained more than most from the rule of the Empire. At foundation, it was two territories and an obvious base from which to expand. Early campaigns west from the Riding added the Mourne to the Marches land. In the time of the Empire's glory, they struck north and west and reached the sea to bring Mitwold into Empire and gain themselves a coast. Bregasland was added in alliance with the merrow by command of a later Emperor. Dawn may proudly boast that it's never lost a territory, but the Marches has gained much, much, more than its older neighbour.