What is tai chien chicken?

"Tai Chien" chicken is not a recognized breed of chicken. It's possible that you are referring to one of the following:

* Taipei Chicken: This is a breed of chicken native to Taiwan. They are known for their unique appearance, with black plumage and a comb that resembles a crown.

* Taiwanese Chicken: This is a general term that refers to any type of chicken that originates from Taiwan. There are many different breeds and varieties of Taiwanese chicken, including the Taipei Chicken mentioned above.

If you can provide more context or details about the "Tai Chien" chicken, I might be able to help you further. For example, where did you encounter this term? What information are you looking for about it?