A ring road is a road that goes around the edge of a town so that traffic does not have to go through the town center.
National Highway 01 or NH01, formally called the Ring Road, is a 2,200 kilometers two-lane road network circulating inside Afghanistan, connecting the following major cities (clockwise): Kabul, Maidan Shar, Ghazni, Kandahar, Delaram, Herat, Maymana, Sheberghan, Mazar-i-Sharif, Puli Khumri and back to Kabul. It has extensions that connect Jalalabad, Bamyan, Khost, Lashkargah, Zaranj (Route 606), Farah, Islam Qala, Torghundi, and Kunduz.
It is also a part of AH1, the longest route of the Asian Highway Network. National Highway 01 consists of four major sections, NH0101 to NH0104, linking the major economic centers.
The road has been rebuilt and re-opened in 2003. Most work on that stretch was done by Turkish, Indian, and local companies. Japanese companies were also involved near the southern Afghan province of Kandahar. In the west, Iran participated in the two-lane road construction between Islam Qala and the western Afghan city of Herat.
According to Wikipedia