History
Shu'halo are the ancient ancestors of the tauren, children of the soil wrought by the Earthmother at the Dawn. Larger, more bestial, and deeply connected with the wilds in ways tauren can only hope to reclaim, their relationship with present-day dwellers of Kalimdor can be likened to the ties between ogres and gronn.
The Great Hunt
It was in these early days that the Great Hunt had no vague purpose; as children and the greatest protectors of the Earthmother, the Shu'halo kept their muzzles to the wind and sought shadows out wherever they formed, beating back the tides of darkness. Often successfully. Sometimes not.
Corruption
Sadly, some Shu'halo hearkened to the calls of the Old Gods. These lost souls entered into terrible conflicts with their own (uncorrupted) kind, and such confrontations, combined with Cenarius' departure, the waning of druidism, and the arrival of the centaur caused the demoralized Shu'halo to become relatively tame over the ages, resulting in the tauren of today.
Present
As the trend of calling themselves Shu'halo would indicate, the tauren are scarcely aware of what they have lost, due in no small part to the ravages of the centaur resulting in the complete destruction of many tribes, and their own word-of-mouth method of preserving information. The Great Hunt of today is merely the battered memory of something that has been deprived of its original meaning, though perhaps found new substance no less honorable. With the strengthening of the Bloodhoof Tribe and their pact with the Horde, some fear the tauren will stray even further from the already whisper-quiet knowledge of old.