The Hankans were a race of humans from the planet Hanka who were once under the occupying force of Goa'uld System Lord Nirrti, who altered their biochemistry in the hopes of creating a hok'tar, an evolutionarily advanced human, which she hoped to one day take as her new host. When SG-7 arrived on Hanka and Nirrti feared her experiments would be discovered by an enemy, she released a virus that left all but one of the population dead. The only known survivor was Cassandra.
In their teenage years the Hankans would suffer what they called the "mind fire," in which they would fall ill to a life-threatening fever and instinctually go into the forest. By touching a glowing hand on a tree they would be drawn to a warm fire where transport rings would sweep them underground to Nirrti's hidden laboratory. The lab was her primary base for the experiments, and there she would cure the illness and send the children back home to pass on their advanced genes to the next generation.
The Hankans were a simple and peaceful people who thrived within their environment. From the structures near the Stargate it can be determined that they were a fairly advanced race in terms of technology, though not to the level of Earth. (SG1: "Singularity", "Rite of Passage")