Cultural contamination was a concern among warp-capable species at least as early as the 20th century, by which time a Vulcan team stranded on Earth hesitated to interact with the Humans. (ENT: "Carbon Creek") In the 22nd century, the Vulcans had adopted a policy of non-interference with less technologically advanced societies. (ENT: "Broken Bow") Under the guidance of Vulcans, notably T'Pol, Earth's first warp 5 starship, the Enterprise slowly began to adopt a similar policy despite initial difficulties like those encountered on Valakis. (ENT: "Dear Doctor")