In ancient times, the city of Rohan was the capital of the Roman province "Rohan". After the first decline, before Emperor Constantine reinvigorated the empire, it was sacked by orcs. Since then, Marspray has been the provincial capital.In the years since, Rome has declined again and Rohan became an independent kingdom. Despite being centered around Marspray on the coast it always kept the name Rohan. A century ago, the power even of the king waned and the realm was on the edge of barbarism when the wizard Ezekiel reformed an ancient order, the Rohirrim, and reunited and reclaimed the kingdom of Rohan.
His heirs sit on the throne in Marspray still, and his has been a just rule and the kingdom has flourished. While orcish bandits are still a threat on the periphery, they are virtually unheard of in the core. Travel to and from the rest of the empire is still uncommon, but it is at least relatively safe these days.