Saikaido is one of the main 'circuits' of TokugawaJapan. Literally translated, it means 'western sea road', now known as Kyushu. Similarly, Hokkaido is the northern sea circuit. Nankaido, which includes all of Shikoku, is the southern; Tokaido is the eastern, made famous by the wood-block prints of Hokusai and Hiroshige.
After the Reformation of the Taika Era (645) and the establishment of an elaborate central government system with administrative and judicial institutions modeled after the Tang Dynasty in China, a road network covering all of Honshu, Shikoku, and Kyushu was established.
This public road network system on a nationwide scale is the system of Seven Roads, and it included the famous Tokaido, Tosando, Hokurikudo, San-indo, San-yodo, Nankaido, and Saikaido.
They were built by adapting to and overcoming the restrictions of Japan's complex topography, and became the prototype of highways and roads in later periods.