The Chrome Dragon was bred to guard treasure, making it one of the few breeds of Dragon that were domesticated. However, most are now feral and should be considered highly dangerous if encountered.
Chrome Dragons are entirely covered in shiny, shimmering metallic plating. Chrome dragons are lithe, agile creatures that can move around in tight spaces with blinding speed. They can control the reflective quality of their scales, dulling themselves down to blend with stone castle walls, or increasing their shine to mimic statues and other valuables in the hoards they've been assigned to guard.
Chrome Dragons are thought to have been bred by ancient kings of Babylon and Persia. Thus, their forebears are thought to include Desert Dragons, Cave Dragons, and other dragons from that region. Eventually, these dragons spread to other regions. Over time they began to covet the treasure hoards they were tasked with guarding, leading many treasures to be abandoned forever and given over to the fearsome dragons.
It's unknown how many Chrome Dragons are left, as many are still likely guarding long forgotten treasure. They are rarely seen above ground, so it is difficult to get an accurate account of the population.