Sphinxes

Sphinxes are creatures from Greek and Egyptian mythology. They combine physical attributes of humans, birds, and lions.

Sphinxes in "The Horse of Bronze"
Sphinxes are the traditional enemies of centaurs. When contact with the Tin Isle was lost, and Centaurs were no longer able to import tin and thus to alloy copper into bronze, the sphinxes enjoyed a significant military advantage. They pressed this advantage and won a major victory over their foes in Turkey. This victory prompted the Centaurs to realize the severity of the crisis to which their tin shortage subjected them, and to mount several expeditions to attempt to secure sources of the metal.