You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Genghis_Khan

Context:
Genghis Khan realised that he needed people who could govern cities and states conquered by him. He also realised that such administrators could not be found among his Mongol people because they were nomads and thus had no experience governing cities. For this purpose Genghis Khan invited a Khitan prince, Chu'Tsai, who worked for the Jin and had been captured by the Mongol army after the Jin dynasty was defeated. Jin had captured power by displacing Khitan. Genghis told Chu'Tsai, who was a lineal descendant of Khitan rulers, that he had avenged Chu'Tsai's forefathers. Chu'Tsai responded that his father served the Jin dynasty honestly and so did he; also he did not consider his own father his enemy, so the question of revenge did not apply. This reply impressed Genghis Khan. Chu'Tsai administered parts of the Mongol Empire and became a confidant of the successive Mongol Khans.

Question:
Which Khitan prince became an important administrator in the Mongol Empire?

Chu'Tsai