The Poodle's history is as intriguing & complex as the breed itself! Because his origins are so ancient, and because there are references in art & literature to Poodle-like dogs in several European countries dating back to earlier than the 12th Century, it is difficult to be precise about his beginnings.
Over many, many centuries his appearance and temperament have little changed.
"If you want to know about the soul of the dog, what makes him tick, you have to go back to the original purpose for which he was designed." The Poodle was originally developed as a water dog in Russia and Germany but, it was perhaps the gypsies, who were itinerate travelers and very fond of performing dogs, that were responsible for the wide distribution of the Poodle. "Gypsies," she said, "quickly latched onto the Poodle and it became their favorite performing dog.The square shape of today's Poodle is derived more from his function as a performing dog than that of a retriever. This square shape does not hinder his work as a retriever but makes him a dual function dog." ....Dorothy Macdonald
Dogs bearing the resemblance to poodles have existed for thousands of years
Caesia 1 denarius - Lucius Caesius, c.112-111 BC The dog on the reverse side of this coin is a proto-Poodle--a water dog--a water spaniel--wearing the working version of what is now called the Continental clip, complete with leg-bracelets.The men look as if they are carrying a rich harvest of Mallard ducks hitched by their necks to the hunters' belts.
The most significant evolution is that he became established in 3 sizes - the Standard Poodle (the largest of the varieties. Technically over 15" tall, but most Standards will be 21-26" tall), the Miniature Poodle (just remember M for Medium-sized... he's under 15" tall) and the Toy Poodle (the smallest Poodle, at under 11" tall)
Though he is often misrepresented as being 'posh' & highly strung, his remarkable intelligence, athletic body & sensible good nature has seen the Poodle used throughout history in all kinds of jobs - war dog, circus dog, police dog, guide dog, service dog, companion dog. But he is most celebrated for his incredible natural talent as a hunting dog. His ability in water, combined with his remarkable nose & initiative made him valuable as a hunter & retriever of wild birds. His nose has also been put to good use hunting for truffles.
From his job as a water dog his signature haircut evolved. His thick, curly, non-shedding coat grows profusely all over his body. This made his job difficult - his coat got caught on vegetation when searching for game in heavy cover & it became water-logged when he swam. As the cold European climate made it neither kind nor practical to shave him all over, just his legs were clipped short to allow freedom of movement. A 'jacket' of hair was left on his body to keep him warm, as well as bracelets on his legs to protect the joints, circles of hair on his hips to protect the joints & underlying kidneys, and some hair was left on his tail to protect it. Throughout history, the hairstyle has become stylized but the basic functional pattern remains the same.
The Poodle History Project by Emily Cain has a wealth of information covering Poodle History