The development of bronze was so significant to human history that its emergence in cultures around the world is referred to as the bronze age. Around 3500 BCE, smiths in western Asia smelted copper, which was soft and plentiful, with the much rarer and more brittle tin. The resulting fusion was more durable than any metal previously available to humans, and became sought-after for weapons and armor. By 2500 BCE bronze had spread to the Aegean world, and over the next 500 years travel throughout Europe. As with many technologies developed for war, bronze soon became adopted as an artistic medium. Sculptures in bronze have lasted millennia, and bronze is still used today for public art, either polished to a golden hue, or left to accrue a regal green patina.