The muggle world never separated from the wizarding one. The combined result of the muggle drive for innovation and wizarding resistance to it is that the whole world is steampunk. The muggles built their cities in the sky to avoid destroying the land, and hogwarts is the most respected magical university in the world, positioned as it is on the very edge of the heavens, among the stars. It's great tower reaches down into the thicker atmosphere and acts as a tether to those parts of the world whose power and progress are insufficient to reach up so high. Blood Purity is a lesser factor in society, and prejudice between muggles and wizards is all but non-existent. This changed with World War One. The flying cities battling over ideas of supremacy, and for access to landbound docks and resource deposits. With the combined powers of wizard and muggle society, the weapons were far more devastating. The consequences of using them less permanent by far. This led to war to end all wars, a war in which a man could have his legs ripped off only to re-attach them in hours, or regrow in weeks. The battlegrounds were the skies themselves, and with so little cost of injury or failure, the end of the battles only came when the will to fight ran dry. Tom Riddle saw this, he saw the devastating powers unleashed by the combination of magic and science, and he resolved to divide them. So it was that he launched his own campaign, a campaign to divide and sever the peoples of the earth, to draw lines where there had been none. It was into this world that Harry Potter was born.