Kria was a female from the River People Clan from pleistocene era. (COMIC: Medicine Man)
She was "bound" to Meerok. (COMIC: Arena of Fear)
She, Nekma and Meerok were kidnapped by the Monaxi and forced to fight or be punished. They helped the Tenth Doctor and Munmeth to defeat the Monaxi. (COMIC: Medicine Man)
Kria, Meerok, the Doctor, Munmeth and many others were then transported by Ebonite via a time bridge to 21st-century New York City and placed in the Arena of Fear, a miniaturised environment. Ebonite tried to erase their memories but the Doctor taught them how to resist it. Together they managed to defeat Ebonite, at the cost of Meerok's life, which was a heavy blow for Kria. Munmeth invited her to join him and Effrid Blunk's team in their quest to relocate the surviving Neanderthals. (COMIC: Arena of Fear)