Originally named the Sind-Pishin State Railway, this strategic railway line was constructed by the Scinde, Punjab & Delhi Railway. Construction began in 1879 and was completed in 1887, which by then was part of the North Western State Railway. Quetta was always considered as an important strategic destination by the British Raj, as they feared the Russian Empire could advance from Afghanistan into Quetta, thereby threatening its rule in South Asia. On 6 October 1879, work on the first section from Ruk (now Rohri) to Sibi (at the entrance of the Nari Pass) and was completed by 14 January 1880. The track had been laid in 101 days across the water less desert by 5000 men and their animals. In 1880, orders were issued for the line to be extended from Sibi to Quetta and onward to Pishin via the Harnai Pass and would become known as the Kandahar State Railway. It was initially thought that the Harnai pass was more suitable for broad gauge than the Bolan Pass. In 1883, construction began in secret and known in public as the Harnai Road Improvement Scheme. From Sibi, the line ran southwest, skirting the hills to Rindli and originally followed the course of the Bolan stream to its head on the plateau. By February 1884, the line had only reached Zardalu. The tough terrain as well as the destructive action of floods led to the abandonment of this alignment. A new extension was thus proposed from Sibi through the Mashkaf Valley and Bolan Pass to Quetta and onward to Chaman in 1885. The line reached Quetta in March 1887, and reached Chaman in January 1892. The section between Khojak and Chaman required the construction of the longest railway tunnel in the North Western State Railway system.