The exact explanation for the arrival of the Bloodmoon Orcs to the territory northeast of Wharftown remains a mystery to scholars, but all speculation points to the ruling powers of Stonehold - later renamed to Wyrmhold after its conquer by an evil dragon.
Around the turn of the 13th century, Stonehold was a fortress constructed beyond the watchful eyes of the Holy City of Kohlingen, the Gem of the Trackless Sea, Cordor, and the increasingly insular village of Winya. A rapid succession of rulers dominated this fortress dubbed Stonehold (many of these rulers falling either in battle or to treachery), all with the intent to gain dominion over as much of that region as possible. Accounts of those rare few granted diplomatic audiences with the leaders of Stonehold claim that they were power-hungry tyrants unsatisfied with their lot in life. Claims have been made (and may, in fact, be nothing more than historical revisionism framed by those who defeated the rulers of Stonehold) that these petty tyrants were often guilty of either leasing or outright selling their souls to otherworldly powers for temporal gain. In addition, families still claim to this day to be descended from human slaves held in captivity by the rulers of Stonehold and forced to commit "unspeakable" acts which have understandably never been spoken of. Thus the brief life of Stonehold was dark and bloody, though the oldest humans in Amia today remember the strongarm of Stonehold: the Bloodmoon Orcs.
The Bloodmoon Orcs are widely regarded to have been half-orc slaves that the rulers of Stonehold spirited onto the island, quite possibly through an open portal within the fortress. After completely disrupting the inland trade routes north of Wharftown in the valleys, the Bloodmoon Orcs were discovered to have, with surprising rapidity, established their own territory in the pass between the hills, now dubbed Bloodmoon Pass. They constantly threatened Wharftown and Winya alike, and even briefly occupied Uhm before being forcibly recalled to defend Stonehold against a combined onslaught.
In the wake of the death of an infamous sorceror who wielded the might of the Mylocks on behalf of Stonehold, the Bloodmoon Orcs were likely struck by the promise of freedom from their masters. The rulers of Stonehold had no time to bolster their ranks with the loss of the Mylocks before the Bloodmoon Orcs turned against them, as well, demanding the territory they had claimed just beyond the borders of the Stonehold fortress as sovereign. It was not granted peaceably, but was inevitably earned when the conflict was ultimately disrupted by Stonehold's unavoidable decay and conquest by a dragon. By the time it was officially renamed Wyrmhold, the Bloodmoon Orcs were understood to have lain violent claim to the Bloodmoon Pass and surrounding areas, and only the hardiest of adventurers dare to tangle with them. Like the Frontier Orcs, the Bloodmoons rarely venture beyond their territory, but unlike the Frontier Orcs, the Bloodmoon Orcs are much less savage and much more organized. Thus, they are regarded as a very real threat by the Holy City of Kohlingen, by Cordor, and by Winya, should they ever decide to mount a strategic attack. Biologists credit the intelligent design of their territory and the consistent threat they pose to their breeding - the clan is composed almost entirely of half-orcs. Historians do not engage heavily in discussions of eugenics and merely site their intense martial training at the hands of Stonehold for their dangerous modus operandi. 
Blood Moon Orc:
This appears to be a grunt of the Blood Moon tribe, wearing salvaged armor wih crude emblems bearing the Blood Moon emblem: A red disc, probably made out of actual blood, shoddily stained onto the armor. The Blood Moon Orcs all have fairer skin than most orcs do, suggesting a relation to the old tries of orcs that inhabited the Skull Crags, which were noted for having tanner skins than their green skinned brethren. It weilds a rusty morningstar and yells savage curses at you as it rushes at you.
Blood Moon Archer:
This Orc of the Blood Moon tribe has a crossbow that it assuredly stole from someone else on a raid, and bolts to go with it. It levels it at you and fires bolts, yelling in Orcish all the while. Its armor is lighter than its kind, and slightly more haggard. It would seem the archers don't get first pick of armor from raids.
Blood Moon Chieftain:
This Orc is dressed in finer armor than the rest of his tribe, and has a helmet to match, a rarity among the rag tag salvaged troops. You quickly realize he must be an important member of the tribe, if not the leader. In his hands is a thick bladed bastard sword, and he commands the other orcs in the fight, even as he swings the blade towards your neck.
Blood Moon Elite:
The Elite of the Blood Moon Tribe are allowed first pick (after the tribal leader of course.) when it comes to selecting pieces of armor, weaponry, and other equipment, and it shows in this specimen. He already looks to be more msucular and adept at fighting than his kin, and the better equipment only gives him a greater edge against his foes, i.e. you. This particular orc has heavy armor, and a double ended mace, steel studded.
Blood Moon Mystics:
The shamans of the tribe appear to be directly from the Orc Tribe just near Bendir Dale, since they look nothing like the Blood Moons, yet they wear their emblemage and live in their caves. The greenskinned mystics provide spells and help to their allies, as well as weilding a quarterstaff in combat. The unanswered question remains though: Why are the greenskins here and not with their tribe?
 Lore Forum - Orcs
Staff written creature descriptions by Tormak.