Shallash was an historic figure in the Tellarite culture, the second liberator of the Tellarite people.
In 2161, Captain Jonathan Archer included a reference to Shallash in a speech he prepared for the signing of the Federation Charter. Before delivering the speech, Archer had difficulty pronouncing the name correctly, referring to him as "Challash". (ENT: "These Are the Voyages...")
This character is only mentioned in dialogue.
Cpt. Archer's trouble with pronouncing "Shallash" correctly might indicate it to rather be the name of a historic figure than a contemporary person as of 2161.