I don't mean to sound trite but it came from mines.

Copper is one of the few native metals these are metals that occur in concentrations of a pure element. If you walk around the right place you'll eventually stumble upon a hunk of copper lying partially exposed on the ground. This copper will have the traditional verdigris (green color like the Statue of Liberty). We can't know for certain as copper predates written history but we theorize that somebody found this pretty green rock and hit it with another rock. Copper is relatively soft so in ancient times they would have found that if you work carefully and get a bit lucky you can beat a hunk of native copper into a decorative or useful shape.

Native Copper is generally formed around volcanic areas. The copper begins mixed in water below the surface as this water is heated it moves through vents toward the surface. The copper begins to collect along the walls of these vents and eventually you have a long copper vein. If the formation with the native copper is weathered bits might fall of and you get the hunk of copper I talked about in the earlier paragraph. Nearby you are likely to find a wall of some kind with that same telltale green color showing in some spots. Now just follow the vein.

As you probably know copper is a good conductor of heat. The rocks around it not so much. At some point people discovered that you could build fires at the start of a vein and the heat would travel along the copper heat it causing it to expand and break the rock around it. This allowed ancient people to mine copper from rock that might otherwise have been too hard to mine with stone or bone tools.

Natural copper occurs throughout the world. There is no single source for the copper that created the Bronze Age.

Interestingly the copper was the easy part of the Bronze Age. Bronze is a mixture of copper and tin. Copper and tin rarely exist in the same area. Perhaps the single most important factor in creating the bronze age was trade routes. Somebody had to find copper somebody had to find tin and then they had to be brought together to make bronze. Bringing these elements together required development of complex systems of trade.

The book A History of Metallurgy by R.F. Tylecote provides lot of details about locations, composition and processing of copper by the ancients.