Curzon believed Russia to be the most likely threat to India, Britain's most valuable colony, from the 19th century through the early 20th century. In 1879 Russia had begun construction of the Transcaspian Railway along the Silk Road, officially solely to enforce local control. The line starts from the city of Kzyzl Su, formerly Krasnovodsk (nowadays Turkmenbashi) (on the Caspian Sea), travels southeast along the Karakum Desert, through Ashgabat, continues along the Kopet Dagh Mountains until it reaches Tejen. Curzon dedicated an entire chapter in his book "Russia in Central Asia" to discussing the perceived threat to British control of India. This railway connected Russia with the most wealthy and influential cities in Central Asia at the time, including the Persian province of Khorasan, and would allow the rapid deployment of Russian supplies and troops into the area. Curzon also believed that the resulting greater economic interdependence between Russia and Central Asia would be damaging to British interests.