Hertasi are popularly considered to be one of the five non-human sentient races created by Urtho, but the work to "uplift" the hertasi was begun earlier, by Sorcerer-Adept Khal Herta. When he died, his work passed to Urtho. The hertasi were mild-tempered reptiles, available in large quantity, and lived fairly simple lives. They could have been described as semi-sentient before the Adepts took a hand. Hertasi had simple structures, organized hunting and fishing, and rudimentary medicine. They began as large, solitary lizards living in swamps, with the intelligence of a dog. Today, they are extremely active, intelligent, cave and tunnel-dwelling, social creatures.
Urtho took the approach of increasing the intelligence of hertasi social leaders, and encouraging them to breed with their subordinates, and then increasing the intelligence of their offspring. It created a surprisingly seamless acceptance among the hertasi for those who are far smarter than any had been before. Part of the uplift, however, was also instilling in the hertasi that they should be appreciative for what they had become.
Hertasi still resemble those early lizards: they have pointed snouts and sharp teeth, tails and scales, and they are cold-blooded. Their night vision is quite poor, but they have excellent day vision. They are smaller than humans, but incredibly strong and clever, and very well-spoken.
Hertasi are active in the summer, and if they do not live in a Vale, they get sluggish in winter like all other cold-blooded animals. During the cold months they sleep as well as craft, making wooden carvings, clothing, and other utilitarian and decorative objects. If it gets too cold, hertasi can get very sick, and sometimes die.
They have a driving urge to feel useful, and many live and work in the Vales with the Tayledras or with the Kaled'a'in of k'Leshya. They exchange their services (food preparation, cleaning, making of clothing or acting as scribes and historians) for food, protection and warmth. They are not subservient in this, more along the lines of down-to-earth friends who realize the great mages will forget to eat, sleep, and change their socks if it weren't for these little allies. They prefer to live in the ground in burrows or caves, often near marshes, and they are uncomfortable in high places. They grow rice, breed frogs, hunt and fish (using small bows and arrows, fish spears and sickle-shaped daggers).
Hertasi pay great attention to detail; they are master craftworkers and love ornamentation. This means that they dislike ugly, under-decorated clothing and badly cooked meals. They will often "steal" clothing they feel is inferior and make something they consider to be more worthy. One or more hertasi will attach themselves to a particular human they think has style (like Firesong) and will predominantly taken care of their chosen individual.
In a fight they often allow their surroundings to do their work for them (since they often live near marshes there is quicksand and sinkholes in which their enemy can be trapped), but they also fight as a group, using their hunting and fishing weapons with great success and overwhelming their opponents. Hertasi also seem to possess a lot of stealth, which has been remarked upon both in everyday work and in battle.
The hertasi motto is "We can do this." 
Though more hertasi are listed, these are the most notable:
- Gervase - early mage of the White Winds School
- Gesten - Amberdrake's friend
- Lyam - Tarrn's assistant
- Nera - Darkwind's friend
- Rork - caregiver to Sparrow in the Sparrow and Cloudbrother Miniseries
- Sherra - a swamp guide