First contact with the Kreetassans was made in 2151 by the crew of the Earth Starfleet starship Enterprise NX-01. (ENT: "Vox Sola") However, it was not until a year later, in 2152, that the ship visited Kreetassa.
In addition to humanoid species, Kreetassa was home to plant life in the form of large trees including sacred Alvera trees. The planet also supported pathogenic lifeforms, harmless to Humans but deadly to Earth canines. (ENT: "A Night in Sickbay")