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Base Information
Classification Herbivore
Status Minor Race
Locomotion Walker
Body Form
Confluence Non-humanoid
Bio-Identenoid Alien
Size 1.0 meters
Weight 40 kg
Languages Yslai
Social Structure Dictatorship
Technological Epoch TL:13-15
Psionic potential Standard
Origin World
Homeworld location Islaiat (Reaver's Deep 0221)
StarportA Excellent: Starship Construction, Overhaul, Refined fuel
Size8 Large (12,800 km, 0.80g - 1.08g)
Atmosphere6 Standard
Hydrographics8 Wet World 80%
PopulationA High (90 billion)
GovernmentA Charismatic Dictator
Law9 High Law (no weapons out of home)
Tech LevelD Average Stellar (holo data)
Primary Star G2 V M8 V
Atmosphere Standard
Off-world presence Yes
Zoetic individuals Yes
Reference Reaver's Deep Sector Sourcebook 26.
Canon No
Also see

The Yslai of Islaiat (Reaver's Deep 0221) are a technologically advanced Minor Non-Human Race with a Non-humanoid appearance.

Description (Specifications)[edit]

The Yslai are a Minor Race of cucumber-shaped "plantimals", widely known for the extremely hierarchical society, often characterized by observers as a "hive society". Their name for themselves is unintelligible to Humans, as the Yslai language is droning sound to which articulated phase modulations, detectable to the Human and Aslan ears as subtle changes in the timbre of the sound.

Physiology & Environment (Ecology)[edit]

The Yslai are a life form that is informally known as "plantimals," which is to say that they display properties of both animal-like and plant-like biota. The Yslai bud in a similar fashion to many plant-like organisms and display herbivorous behavior akin to many animal-like organisms. Their biochemistry is largely compatible with carbon-based organisms such as the Aslan and members of Humaniti.

Body Plan[edit]

Yslai are quite small compared to humans and Aslan, averaging 1.0 meters in height and weighing about 40 kg. They are shaped a little like a Terran "cucumber", and similarly green-colored. It is not known if the Yslai have any autotrophic properties to their green-colored skin, and many Imperial sophontologists suspect that that theory is true. The Yslai, however, will not confirm the theory one way or another. They seem to possess a distinct fear of the medical practitioners and scientists of Charted Space. Yslai are also capable of putting themselves into a form of suspended animation - ideal for the impulse-driven space travel that dominated the culture before the arrival of jump drive, as well as riding out shortages of food on inhospitable worlds. And while an individual Yslai isn't especially imposing, a "colony" of Yslai - each carrying out their specialty in a strict hierarchy - can be a formidable opponent, or rival.


They possess a pair of light/vibration-sensitive "sensor" patches on either side of their midsection, enabling stereoscopic sight and hearing. Yslai "walk" upright on four "limb" stalks, each with an articulable "hand" with three "fingers". The articulation, dexterity and strength of these limbs varies by the specialization of the individual Yslai.

Reproduction & Life Cycle[edit]

Yslai are asexual, and reproduce by "budding" - spawning a small, effectively-cloned version of themselves every few human years. Yslai budding only occurs in times when food and other resources are plentiful enough to support reproduction. Each "bud" is able to function autonomously within a human week of separation, although they only reach maturity (and capability to "bud") after 6-8 human years.

Diet & Trophics[edit]

Yslai's only "food" is a slurry formed from the fermentation and decomposition of vegetable matter which grows in soil rich in elements specific to Islaiat, or in special ammoponic fermentation vats. Aslan find the odor repulsive, but can eat it. Humans find it nauseating, and it is toxic to humans.

Psychology & Philosophy (Mindset)[edit]

The mind of an individual is unimportant; the species as a whole integrated system has plans and goals that should concern other civilizations.

History & Background (Dossier)[edit]

The Yslai as a race, are obsessed with survival - genetically encoded from an earlier time when the race faced incredible existential challenges. This is as a race, rather than as individuals - because outside the Hierarchy, Yslai have no sense of "Self" as humans, Aslan or Vargr understand the term.

Expansionism & Colonization[edit]

As a result, Yslai undertook interplanetary and even interstellar exploration at an incredibly early stage, launching colonization expeditions on asteroids powered by chemical rockets and gravitational influence at what would for humans have been a very early tech level, driven by the discoveries of a series of replicator and hierarchy Yslai, who discovered astronomy before perfecting, for example, electromagnetic communications. Exploiting their ability to suspend their own animation, they launched their first colonization expeditions in roughly -22,000.

Culture & Society[edit]

The Yslai are an adaptive race. The Drone level of the society is focused entirely on carrying out rudimentary (if sometimes sophisticated) jobs toward the good of the community.

While Yslai have little urge to materialism or conquest, they do actively seek conquest and colonize - entirely to increase Yslaia's options in case a world becomes inhospitable.

Social Organization[edit]

The Yslai have a highly hierarchical culture and use a social organization system based upon their own genetics.


Yslai actually refers to four different genetic variants of the same creature:

  • Drone Yslai: The vast majority of Yslai are "Drones" - beings whose intelligence is focused on a very narrow range of tasks.
  • Replicator Yslai: A subtle genetic mutation, capable of working in multiple intellectual channels.
  • Breeder Yslai: Another genetic mutation, capable of external reproduction.
  • Hierarch Yslai: Also capable of multiple thought channels, Hierarch Yslai possess a pheremone-like substance that marks them as leaders.


The vast majority of Yslai are "Drones" - but there is a theoretically infinite number of variations on Drones. Each "Drone" Yslai is "born"/budded as a near-clone of its "parent", and inherits the parent's specialization. Drone cognitive capacity is such that an individual Drone Yslai will have the capacity to exercise a single speciality at a single "tech level" along with basic life-sustainment activities.

Drone specializations vary widely, though. For example, a "Drone" Yslai could be a:

  • "Farmer" - growing vegetation for fermentation
  • "Fermenter" - gathering and fermenting vegetation into the slurry that is the Yslai's sole source of food.
  • "Soldier" - capable of operating in small groups to defend colonies from intruders, at their birth tech level (armed with anything from jabbing spears to laser weapons)
  • "Crewmen" - each type capable of one job needed aboard a wet ship, a system ship, or a starship, from equipment maintainer to gunner.
  • "Calculators" - capable of carrying out specific, often intensely complex, calculations
  • "Nurses" - these drones care for "egg" patches produced by "Breeders". See below.

...and many more.

Drone Yslai have an average life span of 40 human years.


About one in 20,000 Yslai is "born" with the mutant capacity to think in multiple intellectual channels; they are capable of learning things beyond the skills with which they were budded. These are the Yslai who observe, learn and reproduce new ideas for the Yslai to adapt. Replicators are budded with different levels of perception; they have dedicated themselves to evaluating, learning and reproducing everything from technology (everything from human tableware to the Aslan jump drive), intellectual (writing, math, and social activities (like defense and trade)

When one or more Replicator Yslai learns something that needs propagation - anything from Yslaian medicine to Fusion Power - the Replicators begin "budding" drone Yslai with that skill set. Thus, Replication is a trait that only lasts one generation (see "Hierarch" Yslai, below).

Replicator Yslai have an average life span of 35 human years.


About one in 50,000 Yslai are budded with the capacity to absorb genetic material from other Yslai and reproduce them.

Yslai "budding" is caused when small "egg cells" within other types of Yslai begin to create a clone of the parent. Breeder Yslai have the ability - rumored to have come about from millennia of selection and genetic research carried out by "replicator" Yslai - to absorb genetic material from Replicators and Drones to create many duplicates of the original in Drone form. These "egg cells" slough off as small patches of skin tissue, which are cared for by "Nurse" drones" as they grow over the course of a year into genetically-identicial clones based on the original genetic material.

Thus, if there's a surge in need for soldiers, or starship power plant maintainers, or any particular kind of drone, a "Breeder" will be engaged to produce them. After "Fertilization" - the simple ingestion of a piece of genetic material from a "parent" - it takes two human weeks for the egg patch to slough off; a "Breeder" can create 2-12 egg patches a week.

Breeder Yslai have an average life span of 60 years - although their prime breeding career is usually five years; after that, they usually produce an egg patch per month. They grow to be much larger - 1.5 m tall, over 1m thick, and closer to 100kg.


A long-ago mutation allowed a strain of Replicator Yslai to create more replicators through budding. This strain of Replicators also developed an ability to "hum" with a frequency of phase modulation that allowed them to, in effect, "hypnotize" other Yslai, in effect making them leaders.

To make it even more complex - the "Hum" of some Hierarchs allowed them to control up to 20 lesser Yslai. Others could control roughly 20 lesser hierarchs, and so on, through a level after level, each level in the hierarchy roughly 20 times larger than its subordinate levels.

This hum was correlated with higher levels of cognitive intelligence, each level of control implying higher "intelligence". By "Level 3", the Yslai Hierarchs are quite intellectually nimble

The levels:

  • Level 1 - Controls ~20
  • Level 2 - Controls ~400
  • Level 3 - Controls ~8,000
  • Level 4 - Controls ~160,000
  • Level 5 - Controls ~3,200,000
  • Level 6 - Controls ~64,000,000
  • Level 7 - Controls ~1,280,000,000
  • Level 8 - Controls ~25,600,000,000
  • Level 9 - Controls ~512,000,000,000 (theoretical).

For example, Islaiat - population 90 billion - is ruled by a Level 9 Hierarch, controlling four Level 8 hierarchs, each of which controls roughly 20 lower-level hierarchs.

Given the relative rarity of Replicators, they tend to report to Level 3 or higher Hierarchs. Breeders tend to be centrally employed by Level 5 or higher Hierarchs. The larger the grouping and the higher-tech the world, the more drone specialties will be represented in a given group.

Government & Politics[edit]

The government of the Yslai is known as the Islaiat Dominate.

  • Hierarch Yslai are the leaders of Yslai society and form the government and also set the laws of the Yslai.
  • They act through the Replicators and many, many specialized Drones, who also control the "military".
  • Please see Islaiat Dominate for more information.

Language & Letters (Communication)[edit]

Yslai communicate via a tone produced by an internal oscillator. While the tone sounds like it holds a two-pitch hum, it is phase-modulated within the individual Drone.

The first to successfully translate Yslai were the Aslan, who used a highly complex computer algorithm to decode the phase shifts that make up the language and, then, a piece of software that translated the vibration phase changes into Aslan and, later, Galanglic and other languages.

Their name for themselves is unintelligible to humans, as the Yslai language is droning sound to which articulated phase modulations - detectible to the human and Aslan ear as subtle changes in the timbre of the sound - add meaning.

(Language) Toponyms[edit]

All system names (toponyms) in the Dominate are rendered in their Aslan equivalents; the language of the Yslai (the Dominate's main ethnic group) is primarily composed of phase shifts in a dual tone; unintelligible without sophisticated translator software, and not renderable in any form of alphabet.

Technology & Trade (Economy)[edit]

Contact with Aslan traders thousands of years later led to the Yslai acquiring and manufacturing jump drive technology in exchange for what turned into a lucrative mercantilistic trade for the Aslan; Yslai replicators developed the means to process raw materials into manufactured goods, as well as specialized Drones optimized to do the manufacturing. (Caledonian traders found Yslai able to manufacture amazingly ornate artwork as well as other manufactured items.

While Yslai have no internal profit motive, trade, like colonization, was seen as a means to give Yslai a more robust chance of survival.

Military & Intelligence (Force Projection)[edit]

With its huge population, the Islaiat Dominate can support a relatively huge military - but although Islaiat forces tend to be well-led from a strategic perspective, they are generally (but by no means always) less tactically capable.

Indeed, much depends on the strategic and tactical facility of the commanding hierarch - or, at lower levels, the tactical skill bred into the "sergeant" drones that lead small Islaiat units.

Starship Architecture[edit]

Islaiat starships tend to be small, and highly specialized; the "Navy", aka the Islaiat Dominate Navy is composed mostly of "scouts", whose job is finding the enemy, and "battleships", whose job is to kill them.


This race is primarily located in the following areas:


The homeworld of this race is:

World Listing: 1105[edit]

Significant communities of this race are known to exist within the following systems and worlds:

2 of 2 World articles in Yslai
Islaiat  •  Maijarra  •  
startbacknext(2 listed)

References & Contributors (Sources)[edit]

This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Far Future Enterprises or by permission of the author. The page history lists all of the contributions.