This tale ends at the bank of the Wye somewhere near Hereford. It is one of the most fantastic of the medieval legends of faerie encounters. In Walter Map's De Nugis Curialium (1190) he tells the tale of King Herla, one of Britain's earliest Kings.
One day a small man rode into King Herla's court and claimed he was a king as well. In fact a king of many other kings. He proposed an exchange of visits and declared "I will attend your wedding and a year later you will attend mine." King Herla did agree and when his wedding was celebrated, the small king arrived with a large company of servants and a lavish entourage. They supplied everything needed for a perfect banquet, golden goblets and dishes and silken tents.
A year later he came back to King Herla and claimed it was his own wedding and Herla followed him to the small king's kingdom. The entrance was through a crevice in a cliff face. At first the way was pitch black but eventually as they moved down into the mountain it was lit by magical light and they entered a large room where the Otherworld's king's wedding took place. They feasted and reveled for three days and King Herla and his men were sent home with all manner of faerie gifts. Horses, hounds, hawks and hunting gear. A particular gift, given to King Herla himself was a small bloodhound and he was given specific instructions to never dismount on any account until the hound does first, of his own accord.
When back to their own realm and in daylight they came upon a shepherd. King Herla asked news of his queen. The man could barely understand the speech of Herla, for he was a Saxon. But at length he replied that there was indeed some story of a queen by that name who had been wife to a King Herla many many years ago, who, he said, "disappeared in the company of a faerie king at this very cliff and was never seen on earth again. It is now two hundred years since the Saxons came and took possession of this kingdom."
Herla, amazed at this news because he believed he had only been gone three days, almost fell from his horse. It was good luck he did not for some of his retinue who forgot the admonishments of the faerie king before, dismounted and as soon as they touched the ground, dissolved into dust.
Map goes on to explain that from then on Herla and his men were found to ceaselessly ride around Hereford at wild speeds, only at night. Locals called them 'the household of Herlethingus' which means "Herla's host." "Troops were engaged in endless wandering, in an endless round, in awestruck silence, and in them many persons were seen alive who were known to have died."
In the author of this tale's own lifetime it is said that Herla and his endless riding finally came to an end in the first year of the reign of Henry II. The last day the host was seen was one day in full daylight, the entire hose traveling like a living company, with carts and packhorses, baggage, hawks and hounds. There were both men and women among them. The local people were alarmed by their strangeness and silence and gathered up to attack them. But before they could muster, the host vanished on the banks of the Wye river.