The Chiar were a pre-warp culture that existed in the Delta Quadrant of the galaxy.
Biology
Chiar have four legs and a long segmented neck with a flattened head perched atop it. A pair of arms jutted from the place where the neck met the body and ended in six-fingered hands. About one-fifth of a Chiar's body is composed of nanites. Thanks to their nanotechnology, they possess an outer skin capable of changing its molecular composition to suit the needs of the host. (VOY novel: The Nanotech War)
History
Culture
Slavery
The Chiar practiced slavery using servants called thralls. These thralls were subjugated members of their own species, and whose will was under the influence to the nanites of the master.
Nanites
Another facet of Chiar culture is their use in nanotechnology. All Chiar, possess nanites that are integrated with their nervous systems. The nanites keep them free of disease, and they heal damage more quickly than normal medical procedures. A Chiar's nanites take the form of an outer surface similar to skin whoch the Char could through a series of chemicals in the brain command the nanites to change it into whatever is appropriate his/her my situation: thick for cold weather, thin for warm, and so on. In addition it can even serve as crude armor, if necessary. These commands are not just limited to biological changes in the host but could also be used to repair objects and even technology, depending on the damage.
Technology
Besides the Chiar's impressive sciences in nanotechnology they also were on the verge of discovering the secrets of warp travel. By the time of the USS Voyager's visit to Chi, the Chiar had developed its first prototype warp drive, called the Zedrel Drive, by the 'inventor'.