A race I have built up over a long time, with a pretty exhaustive background. Here's the short version. :P

If the Kyyreni (pronounced "K'eye-rennie") were to be encapsulated in one word, that word would be "violent". Most know them as raiders who loot and enslave their way across the land before retreating to their own domains. When they are not marauding their neighbours, they fight amongst themselves; the Kyyreni are locked in an endless civil war that shows no end of stopping.
At least, that is how most see them. Beyond this simplistic observation is a two-tier culture, dominated paradoxically by a base notion of "might makes right", and a Byzantine legal structure that dictates exactly how, when and why "might" may be applied.

If there's a fight taking place, odds are the Kyyreni are in the middle of it. For them, fighting is not only a means to an end; it's a way to pass the time. Kyyreni love to show off their prowess, and if they cannot best their enemies in a feat of arms, they'll show off their intellect or cunning instead.
As a species, Kyyreni like rare and precious things; the rarer the better. They do not place much value in gold, preferring practical materials like mithril or the sacred metal, iron. Nevertheless, they will covet gold as it can be used to buy more desirable things.
Most Kyyreni are very aggressive, especially in their younger years. This aggression tends to cool with age, though few Kyyreni will ever turn down a fight they think they can win.
Despite often appearing fickle and uncaring of others, Kyyreni take oaths very seriously, and few will ever break a solemn oath once given.

Physical Description:
Kyyreni are bestial in form, and are sometimes mistaken for Gnolls due to passing similarities. They stand almost as tall as humans, with digitigrade legs, a wolfish head and the tail and footpaws of a lion. Their bodies are covered in thick fur; sandy blonde for males, with females sporting brown or grey fur. All males develop a thick mane during puberty, as well as 'tufts' on the end of their tail. Females may also have spots or stripes, but this is extremely rare for males.
On the outside of each eye, which are vaguely reptilian in appearance, all Kyyreni have two patches of dark skin that are sensitive to heat.

Kyyreni cultures rarely get along with anyone, save for those who share their general outlook or are deemed too strong to raid. Peoples they cannot attack are usually targeted by Merchant Guilds and other trade bodies, who some might say far more dangerous.
Most Kyyreni have little love for Elves, whose long lives and affinity for magic are inherently distrusted. They respect Dwarves due to their skill at metalworking, and most bestial races for their martial prowess. In general the Kyyreni do not see any race as their equal. This does not necessarily extend to individuals, however, and so there is no reason specific Kyyreni would not be able to respect and admire individuals from another species.

Kyyreni of all alignments can be found, but few ever tend toward Good. Despite their apparently random behaviour, all Kyyreni actions are ultimately dictated by the excessively convoluted social and legal codes their people employ, and as such they tend to be Lawful more than Chaotic.
Kyyreni adventuring far from their homelands are likely to tend toward Chaotic and/or Good alignments, as these individuals would likely have a harder time living there and thus seek escape.

Kyyreni Lands:
The oldest nation of the Kyyreni is found on their home world of Urokon, and is known as the Dawn Kingdom. Most Kyyreni cultures reflect this land to some degree.
The Dawn Kingdom is a collection of semi-autonomous nation states, fiefdoms, empires and other domains. Each subrealm is ruled over by a high ranking Noble Lord, typically a Duke, Count or similar. Below him are the various Earls, Barons, Knights and so forth that make up the "highborn"; the ruling tier of the Kyyreni. The rest of the society are classified as "thralls", "lowborn", "unclaimed" or similar less than flattering titles.
Despite what their name suggests, Houses and their titles are not hereditary; the Houses vie with each other constantly, seeking to locate and gain the favour of up and coming powers whilst isolating and crushing those Houses that have stagnated. To prevent this endless power struggle from spilling into total war, the Houses settle their disputes with ritualised challenges. Naturally, skilled swordsmen are in high demand, and the best quickly rise to the upper tiers of society.
Within the Kyyreni nations, the people proudly boast that a man can, if he has the skill and tenacity, rise from lowly slave to king. In theory this is true, though in practical terms it is almost impossible to accomplish in one lifetime.
Slavery is common within Kyyreni nations, though it is far from the cruel methods used by Orcs, Gnolls and other savages. Indeed, slaves of the Noble Houses can expect to be well fed, well groomed and even educated. Combined with the prospect of remaining on after their freedom, and thus even achieving high station, results in some Kyyreni becoming slaves of their own free will. Though outsider slaves can rarely achieve any power in their lands, some have achieved respected positions within their master's household.

As a species, the Kyyreni will worship any deity they believe will give them power. This results in a polytheistic outlook to faith; few Kyyreni, if any, worship one single God or Goddess.
The race does of course have its own deities, and of these two stand out more than the others.
The first is Kalkar, the God of the Dead. All Kyyreni (whether they believe in him or not) are judged by Kalkar in death. Those who are deemed to have lived an honourable life (it is worth noting that the definition of an 'honourable life' varies quite a lot...) are welcomed into his realm. The rest are cast out; their souls wander the plains in search of a new resting place, or else linger to try and ambush fresh souls and steal their identities.
The second of the main Gods is Vorhol, the Forge God. The Kyyreni believe he created their species in his divine forge by mixing a drop of his own blood with the metal. Thus, the Kyyreni claim, Vorhol created the ultimate weapon - a warrior race that could never be conquered. This race was used to purge their homeworld of a Demon army, and this belief is in part the source of the Kyyreni's distrust of magic. Despite the veneration for Vorhol, the God has no doctrine of his own; he has no desire for anyone, not even himself, to dictate the fate of the Kyyreni.

The primary language of the Kyyreni is "Ruljicyyt" (pronounced "Rul-jig-site") or "Ruljic" for short. It is a complicated language that is made up in part of animalistic sounds that are difficult for Humans and the like to pronounce. Different communities have their own dialects, but almost all Kyyreni can communicate with each other to some extent.
Secondary languages tend to be shaped by their neighbours, both ally and enemy.

Kyyreni names often have an 'eye' or 'ar' sound in them, written as 'yy' or 'aa' respectively. The specific rules of their names are quite complex, however, and it is not uncommon for a Kyyreni traveller to 'commonise' their name for the sake of others (ie: "Taryyk" might become "Tarik"). Names often have silent h's in them toward the end if the final letter is soft, but not if the end is sharp.
Most Kyyreni do not have surnames. Instead, they address themselves as "son of" or "daughter of" their parent (males go by father, females by daughter). The exception is if their family lineage contains an especially famous individual, in which case they will adopt that name as their surname... though the rules as to whether they can do this 'legally' are quite complicated, and highborn are very proud of being the inheritor, or even first successor to a hero's bloodline.
Sample male names:

Sample Female Names:

Stat Adjustments: +2 Str, -2 Int.
Size: Medium.
Base land speed: 30ft.
Low Light Vision: Kyyreni see twice as well as humans in the dark.
Thermal Vision: Kyyreni can 'see' in total darkness of up to 30ft providing the object of surface is emitting a small amount of heat (approx 10oC). This vision is sensitive to differentiate living creatures by thermal sight alone, providing they give off enough body heat.
For warmer objects, such as living things, Kyyreni can spot them up to 60ft away, but cannot make out any details. Very hot objects can be detected further away at the DM's discretion, but should never be visible from more than 90-120ft no matter how hot (it simply becomes background haze).
Note that cold objects are completely invisible to thermal sight.
Sharp Senses: Kyyreni gain +2 to Listen checks due to keen hearing. they gain +2 racial bonus to Track (and possibly Search) due to their sense of smell.
Quick Recovery: Kyyreni require only four hours sleep per night (spellcasters still require eight hours rest to restore spells), and heal twice as quickly as Humans (ie: 1hp per level after four hours rest, 2hp per level after eight hours rest, or 4hp per level after a full day's rest).
Blood and Iron: All unarmed attacks and melee weapon attacks made by a Kyyreni count as Cold Iron for the purposes of overcoming damage reduction if his total Hit Dice are equal or greater than the creature's DR.
Weapon Familiarity: Kyyreni are proficient in using Houseblades (a localised version of the bastard sword) two handed, regardless of class. If their first level is in a class that also gives them proficiency with two-handed bastard swords, they become proficient at using Houseblades one-handed instead.
Speak Language: Common, Ruljicyyt. Bonus Languages: any (see "language" notes above).
Favoured Class: Fighter.

Random Starting Ages:
{table=StartAge]Base Age|Tier 1|Tier 2|Tier 3
12 years

Kyyreni Ageing Effects:
{table=Age]Adulthood|Middle Age1|
|Maximum Age
1 At middle age, and again at old age, -1 to Str, Dex and Con; +1 to Int, Wis and Cha.
* Characters can potentially start below this age. This is fine; 15 is simply the age where a Kyyreni is completely beyond puberty. Culturally, most Kyyreni are considered "adult" at 12, being physically comparable to a 16-18 year old Human.

Height and Weight:
{table=Height/Weight]Gender|Base Height|Height Modifier|Base Weight|Weight Modifier
Kyyreni male
Kyyreni female