Given this reference text on the creation of centaurs, where did the mythology originate?

The centaurs were usually said to have been born of Ixion and Nephele.[6] As the story goes, Nephele was a cloud made into the likeness of Hera in a plot to trick Ixion into revealing his lust for Hera to Zeus. Ixion seduced Nephele and from that relationship centaurs were created.[7] Another version, however, makes them children of Centaurus, a man who mated with the Magnesian mares. Centaurus was either himself the son of Ixion and Nephele (inserting an additional generation) or of Apollo and the nymph Stilbe. In the latter version of the story, Centaurus's twin brother was Lapithes, ancestor of the Lapiths.

Another tribe of centaurs was said to have lived on Cyprus. According to Nonnus, they were fathered by Zeus, who, in frustration after Aphrodite had eluded him, spilled his seed on the ground of that land. 

There were also the Lamian Pheres, twelve rustic daimones (spirits) of the Lamos river. They were set by Zeus to guard the infant Dionysos, protecting him from the machinations of Hera, but the enraged goddess transformed them into ox-horned Centaurs. The Lamian Pheres later accompanied Dionysos in his campaign against the Indians.[10]

The centaur's half-human, half-horse composition has led many writers to treat them as liminal beings, caught between the two natures they embody in contrasting myths; they are both the embodiment of untamed nature, as in their battle with the Lapiths (their kin), and conversely, teachers like Chiron.[11]

A centaur is a creature from Greek mythology according to this paragraph. It can be inferred because numerous Greek gods were referenced in the passage.