The Tllihuh were a warp-capable species that originated somewhere in the Milky Way Galaxy.
History
In 2376, a Tllihuh vessel was caught in an Iconian gateway and became stranded with several other vessels in the Delta Quadrant. Lost and bereft of any way to return home, they accepted Captain Kathryn Janeway's offer of Voyager'sprotection and guidance, joining the multi-species caravan fleet.
On the journey the Tllihuh got into a violent argument with the Iyal due to food shortages. The Iyal were reluctant to provide aid due to facing a similar hardship. Janeway intervened and offered to provide extra rations for the Tllihuh.
During the journey through a Mutara class nebula, the Tllihuh were willing to cross through so long as they could determine the order of vessels that would go through.
Culture
It seems that the Iyal and the Tllihuh had a thriving planetary trade agreement. (VOY - Gateways novel: No Man's Land)