Here’s a surprise: The English royal menagerie of the 13th century included a polar bear. From The New American Cyclopædia, 1869:

In the reign of Henry III, of England … it is curious to record that a white bear was among the collection of wild beasts in the tower of London, for which the sheriffs of the city were ordered to provide a muzzle and an iron chain, to secure him when out of the water, and a long and stout cord to hold him when fishing in the Thames.

“The words italicized seem to identify the species beyond the possibility of error; but one would like to know whence the polar bear was brought, at that early day, so long previous to the commencement of arctic exploration.” Probably it was a gift from Haakon IV of Norway.

See Clara and MacFarlane’s Bear.