The elements of the Legends of the Rohirrim are former knights of the War of the Ring.
The armies of Rohan were almost exclusively horsemen, divided into irregular units, which could include up to 2000 riders. Rohan's armies were more of a very well-trained militia called upon in times of war, with the actual standing army relatively small.
The rule of the Stewards of Gondor was then over. King Éomer and the new king of Gondor, Elessar, renewed their oath of alliance, and reaffirmed Cirion's grant of Calenardhon to the Rohirrim. At this time, Éowyn marries Faramir, Prince of Ithilien and Steward of Gondor, thus joining the lines of Gondor and Rohan.
In the Fourth Age, Rohan remained in peaceful coexistence with the Reunited Kingdom. It became the site of routes where Elves migrated from their eastern kingdoms to Lindon to leave Middle-earth. A few remained behind to help in the reconstruction of Rohan. A Dwarven community developed in the caves of Helm's Deep, which became prosperous from its mining of precious materials.
To protect trade routes and the journey of new settlers to the Reunited Kingdom was established an order of brave Rohirrim former knights of the War of the Ring. This order was originally composed by the race of men but they had several problems to intervene and help dwarves, hobbits and elves who did not trust men. Then the Order of The Legends of the Rohirrim found himself in need to join its hierarchy the various races of the Middle-earth.
Thus, the order thrived and succeeded in maintaining the security of the kingdoms of Rohan and Gondor. Shortly thereafter with the confidence of the various races of the Middle-earth placed in them, they extended the assistance to the four corners of Middle-earth.
The achievements of the elements of the Order of the Legends of the Rohirrim are sung by virtuous bards in all places of Middle-earth.
The chain of Evil has split, however, there remains a possibility that a new Sauron will come. And us kinship of the Legends of the Rohirrim will be ready expecting him.