Historic roads (historic trails in USA and Canada) are paths or routes that have historical importance due to their use over a period of time. Examples exist from prehistoric times until the early 20th century. They include ancient trackways, long-lasting roads, important trade routes, and migration trails. Many historic routes, such as the Silk Road, the Amber Road, and the Royal Road of the Persian Empire, covered great distances and their impact on human settlements remain today. The Post Track, a prehistoric causeway in the valley of the River Brue in the Somerset Levels, England, is one of the oldest known constructed trackways and dates from around 3800 BCE. The world's oldest known paved road was constructed in Egypt some time between 2600 and 2200 BC. The Romans were the most significant road builders of the ancient world. At the peak of the Roman Empire there were more than of roads, of which over were stone-paved. Another empire, that of the Incas of pre-Columbian South America, also built an extensive and advanced transportation system. Much later historic roads include the Red River Trails between Canada and the US, from the 19th century. Such pioneer trails often made use of ancient routes created by indigenous people. Beginnings It is claimed that some of the earliest roads were created by humans who followed already existing paths made by animals, and, in particular, that trails created by the herds of buffalo shaped the routes taken first by indigenous peoples and then colonists, especially in North America: The buffalo, because of his sagacious selection of the most sure and most direct courses, has influenced the routes of trade and travel of the white race as much, possibly, as he influenced the course of the red-men in earlier days. There is great truth in Thomas Benton's figure when he said that the buffalo blazed the way for the railways to the Pacific. That sagacious animal undoubtedly “blazed”—with his hoofs on the surface of the earth—the course of many of our roads, canals, and railways. That he found the points of least resistance across our great mountain ranges there can be little doubt. It is certain that he discovered Cumberland Gap and his route through that pass in the mountains has been accepted as one of the most important on the continent. It is also obvious that the buffalo found the course from Atlantic waters to