After the Xikang-Tibet Highway and the Qinghai-Tibet Highway were opened to traffic, other highways were constructed including the Xinjiang-Tibet Highway extending from Yecheng in Xinjiang to Ngari in Tibet, the Lhasa-Yadong Highway, the Lhasa-Zetang Highway, the Xigaze-Tingri Highway and the Heihe-Qamdo Highway. Sand and stone may only have covered these roads,but they were an embryonic form of modem transportation in Tibet and served as a solid foundation for development of modem highways. Until 1959, before the Democratic Reform in Tibet, the overall length of highways totaled 5,648 kilometers, creating a primary Tibetan road network with Lhasa as the center.