People have relied on location information since before the dawn of recorded history. Cave dwellers once carved maps of hunting routes into mammoth tusks. Such maps evolved as civilizations flourished. The ancient Babylonians fully mapped the borders of their vast empire. Much later, in 3000 BC, Greek scholars improved cartography using mathematical innovations. The Greeks discovered that the Earth was round and accurately computed the planet’s circumference. Greek mathematicians laid the groundwork for measuring distances across the Earth’s curved surface. Such measurements required the creation of a geographic coordinate system: a rudimentary system based on latitude and longitude was introduced in 2000 BC.