Wikipedia
Zouyu is a legendary creature mentioned in old Chinese literature. The earliest known appearance of the characters 騶虞 (zou yu) is in the Book of Songs, but J.J.L. Duyvendak describes that the interpretation of that little poem as referring to an animal of that name is "very doubtful".
Zouyu appears in a number of later works, where it is described as "righteous" animal, which, similarly to a qilin, only appears during the rule of a benevolent and sincere monarch. It is said to be as fierce-looking as a tiger, but gentle and strictly vegetarian, and described in some books (already in Shuowen Jiezi) as a white tiger with black spots.
During the reign of the Yongle Emperor (early 15th century), his relative from Kaifeng sent him a captured zouyu, and another zouyu was sighted in Shandong. The zouyu sightings were mentioned by contemporaneous authors as good omens, along with the Yellow River running clear and the delivery of a qilin (i.e., an African giraffe) by a Bengal delegation that arrived to China aboard Zheng He's fleet.
Puzzled about the real zoological identity of the zouyu said to be captured during the Yongle era, Duyvendak exclaims, "Can it possibly have been a Pandah?" Following him, some modern authors consider zouyu to refer to the Giant panda.