The empire known for its extensive road system, connecting vast territories across South America, is the Inca Empire. The Incas developed a sophisticated network of roads known as the Inca Road System or Qhapaq Ñan, which stretched over 25,000 miles across mountainous terrain. These roads facilitated trade, military movement, and communication throughout their expansive territory, helping to unify the diverse regions and peoples of the empire, which thrived from the early 15th century until the Spanish conquest in the 16th century.