Mars was the first planet in our solar system to master spaceflight, a fact only found out after first contact with the Silis.

Mars, or Barsoom (to use its native name) is mostly dry plains and empty seabeds, with a few small seas dotted here and there.

There are ten native sapients, five derived from arthropoids, and five from primate-analogues

Sarmak

the Sarmaks are the most technologically advanced race on Barsoom, and one of the few to have developed space travel (along with the Okoomians and a few Red Martians)

The Sarmaks are a leathery-skinned, tentacled race who feed on the blood of Martian animals. They reproduce asexually, children being born by "budding" off a parent. Internally, the Sarmaks consist mostly of brain.

Due to this, they are frighteningly intelligent, and have a devastating array of weapons to defend themselves. the only factors stopping them from becoming invaders are the fact that they are from a low-gravity planet (Sarmaks normally move around by hopping, but in Equis-like gravity they are forced to drag themselves across the ground), and that they have among the weakest immune systems of any known species.

Instead, the sarmaks are a mercantile race, trading and delivering goods between other factions.

Erloor

Relatives of the Sarmaks, the Erloor are also hemovores (blood-drinkers) who consist mostly of brain.

Located mostly around the Toonolian Marshes, Erloor are actually capable of flight for the first few years of their life, before they become flightless as adults. They can manipulate chromatophores in their skin to such a degree as to become invisible.

Erloors can often be found in service to the Sarmaks.

Kaldane

Kaldanes are more immediately arthropod-like than their Sarmak or Erloor relatives, but still have a similar internal structure, consisting of a massive brain and a degenerate digestive system.

Like the sarmaks, Kaldanes are asexual, living in societies headed by a "King" who lays all the eggs. a few will hatch into more "Kings", who will either move off to start new colonies, or will fight the current king for command.

Kaldanes have domesticated a species known as the rykor, which resembles a strange, hairless primate with red skin and no head, having a gaping orifice instead. Kaldanes will place themselves where the head would normally be, and through several manipulator tendrils, will tell the rykor where to go.

Ulfi

Native to the Thakkor Marshes, the Ulfi are roughly 3 feet tall. They are a tribal race, but are less war-like than many other Martian races.

The Ulfi are capable of changing their color to become near-invisible, allowing them to hide and ambush their enemies and prey. The young are raised communally.

Ulfi lay eggs, which hatch into larvae. These spin a cocoon after several years, emerging after several months as young adults.

As with many Martian races, they are a monarchy. However, it is the females which lead the community

Zigg

Tribal natives of the Toonolian Marshes, the Ziggs are one of the few Martian races to have discovered the bow and arrow. They dip their arrows, as well as their speartips, with a paralyzing toxin, causing long-term paralysis in their prisoners and prey.

They make complicated web-nests, and their religion centers around worshipping the current ruler as a living god.

Thark

"Leave a Thark his head and one hand, and he may yet conquer!"

The tharks are the largest of the Martian races, the males standing up to fifteen feet tall and the females up to twelve feet. They have green skin, small antennae-like ears just above the eyes, and large tusks. In the males these tusks extend upwards to the level of the eyes. The eyes themselves are large and wide-set, with snowy white sclera and blood red irises. Each eye is capable of moving independently of the other. Their women differ in the fact that their skin color is lighter, their tusks extend up to the level of their antennae, and they also have vestigial fingernails.

Like all other Martian vertebrates, they lay eggs; newly laid eggs are the size of a goose egg, and the young take up to five years to hatch. The young are miniature replicas of the adults, standing 3 to 4 feet in height when hatched, with yellowish-green skin that darkens as they age. The most distinct trait of the species is their six limbs - two arms, two legs, and an intermediary set of limbs that can be used as arms or legs.

Understanding the culture of the tharks can be linked to understanding how they are born and how they spend their childhoods. Each year, the women bring forward up to thirteen eggs; the eggs that meet certain weight, size, and specific gravity tests are taken to a secret underground vault where it is too cool for incubation to occur. Each year a council of about 20 chieftains examines the eggs, and all but about 100 of them are destroyed, preserving only the most perfect for incubation. Once the five-year hatching period ends, any eggs that do not hatch on time are unwanted (it is also important to note that if one green horde comes across another hordes incubator they destroy it and the eggs inside).

Once born, the youths are scooped up by women of the community; if any of the children prove deformed or defective in any way they are promptly shot without a tear shed by anyone. The women raise them, the only aspects of their raising being the teaching of language and use of weapons, which they are given during their first year. The erstwhile mothers develop no feelings or attachment to their children - the children belong to the community and as a result parental love is completely unknown to them. From birth, they know no fatherly or motherly love, and they have no concept of the word home; they are taught that they are only suffered to live until they can demonstrate by their physique and ferocity that they are fit to live. It is likely that this horrible system is what resulted in the loss of the finer feelings and humanitarian instinct of the general population of their people.

Of course, one must also understand how they live their everyday lives. The people are barbaric, they have no art and no written language, and have never constructed any structure beyond the necessary incubators. Their sense of humor is cruel, laughing at death and suffering. They are constantly at war with each other. They detest mining and physical labor, and all things of value are produced by the females of the species. Concerning law, they make new laws only as it becomes necessary; a new law for each emergency. They are unfettered by precedent in the administration of justice. Customs have been handed down by ages of repetition, but the punishment for ignoring a custom is a matter for individual treatment by a jury of the culprit's peers.

One of the more notable aspects of the green culture is their domestication of many of the various beasts that inhabit Barsoom, and the usage of these creatures in their convoys.

Orgus

The youngest of the Martian races, the orgus are directly descended from the Tharks... specifically, from eggs suffering a specific set of mutations.

For unknown reasons, a single egg suffering heavy mutation was allowed to live. the resulting hatchling grew into a 5-foot runt with brown skin, underdeveloped median limbs, forward-facing eyes, and a smattering of small cone-like horns.

This individual was allowed to live, and established his own kingdom, trading with Tharks for eggs showing the same mutations he had. (as a note, the name "Orgus" is a joke that the race adopted for themselves, as Orgus literally means "bad egg")

And so the Orgus grew in size, and bred true, becoming a new race. The Orgus retain the warrior culture of their Thark ancestors, but also form familial attachments among themselves, with male-female pairs taking care of their young.

Sea Martians

Native to the Opal sea near the northern pole, little is known of these near-animalistic people.

the Sea Martians are unusual for being one of a small group of martian vertebrates with only four limbs, though skeletal remains show a middle pair of degenerated limbs.

Pfifltriggi

They delight in digging. What they dig they soften with fire and make things of it. They are little people, smaller than you and long in the snout, pale, busy. They have long limbs in front. None can match them in making and shaping things as none can match us in singing.- a Hrossa describing the Pfifltriggi

The Pfifltriggi are located in the southern region of a great valley, near the reaches where it connects to Valles Marinis, shielded from the south, east and west by the Tharsis highlands. The Kaolians (citizens of the red martian city of Kaol) are aware of the Pfifltriggi and have trading relations with them, as do the Sarmaks of the Tharsis highlands.

They live in matriarchal societies, but are secretive, so little else is known about them

Okoomians

Native to the region of Mars known as Okoom (near the south pole), the Okoomians are easily recognizable by their black feature-less skin, a pair of large eyes and a usually tranquil, smooth-talking nature which often hides ambitious and belligerent intentions. Height is highly variable among individuals: while some are really short, others reach more respectable stature. Only females of this species have hair. While seemingly featureless, Okoomians do in fact have mouths, though they are usually not noticeable when closed.

Okoomian is imperialistic, and ruled by a single monarch, and they have shown to be extremely expansionist, claiming even the smallest asteroids in the name of their homeworld.

3841514 Ah, no Red Martians? Also... Excellent!

3855615 Too human-like.

3855615 Added some. Still saving the human-like ones for another post.

We're talking

BURROUGHS: Orovars, Therns, Okars, First Born, Red Martians, and Goolians

KLINE: Ma Gongi

ARNOLD: the Thither-folk

POPE: Nilata

LEWIS: the Sorn and the Hrossa