1791, Voyages And Travels Of An Indian Interpreter And Trader, page 69:
In about an hour they returned very much intoxicated, singing their dead war songs, and every warrior naked, painted black from head to foot: as they approached the house in Indian file, each one repeated the following words […]
Usage notes
Usually used as walk (march, approach, etc) Indian file (adverbially) or walk in Indian file. Until the 1800s, the form walk in an Indian file was sometimes encountered.
Etymology
Attested since the 1700s, because Native Americans traversed woods in this way.