Sumatra was a station on the Milwaukee and the highest point between Miles City and Harlowton. When trains were still run by coal engines it was necessary to put on a "pusher engine" to make it up the hill to Sumatra. The station was first called Summit, and just how the name evolved into Sumatra is unclear. In the days before the railroad, Sumatra was on the old trail that connected Fort Musselshell with Fort Custer in Big Horn County. (from Cheney's Names on the Face of Montana, Mountain Press Publishing Company)
Sumatra is a small community in between Ingomar and Melstone in central Montana.