Originally "Earl Grey Tea" was made with unsteamed China black tea, but is now usually made with Indian and Sri Lankan (Ceylon) black tea. Many sources state that Charles Grey, 2nd Earl (also Baron Grey and Viscount Howick) was given the recipe by a Chinese mandarin with whom he was friends (and/or whose life either he or another British diplomat saved).
The Bergamot Orange is the flavoring used in Earl Grey Tea. Oil of bergamot is extracted from the peel of the bergamot orange (Citrus bergamia or Citrus aurantium bergamia), a small pear shaped sour orange which is cultivated today mostly in southern Italy.
Latest genetic research indicates that the Bergamot orange is most likely a cross (natural??) between the sweet or pear lemon (Citrus limetta) and the Seville or sour orange (Citrus aurantium) [First International Citrus Biotechnology Symposium, August 2000)] The sour orange is native to southern Vietnam, hence the Chinese connection.
This is NOT Bergamot or Bergamot mint; they are different plants in the mint family, also called bee balm or Oswego tea.