Multiple realities(covers information from several alternate timelines)
H'atoria was a planet orbiting the primary H'atoria, in the Beta Quadrant.
In 2016, a Vulcan starship crossed into Klingon space near H'atoria and was immediately destroyed by the Klingons. In the aftermath, Vulcans established a policy of firing first when encountering Klingons, earning their respect and eventually leading to the establishment of formal relations. (DIS: "The Vulcan Hello", "Magic to Make the Sanest Man Go Mad")
While it was not explicitly stated, this was strongly implied to have been the first contact between Vulcans and Klingons.
As of the late 24th century, it was home to a small Klingon colony, which was located near the border with the Federation.
In an alternate future timeframe, Worf was governor of H'atoria. (TNG: "All Good Things...")
This planet was only mentioned in dialogue.
"ha-TORE-ee-uh" was the pronunciation for this planet's name from the script pronunciation guide.