The story
From tump + line, "tump" is an apheresis of mattump, metump, possibly from a Penobscot descendant of Proto-Algonquian *wetempi (“head”).
Etymology from Wiktionary, CC BY-SA 4.0.
tumpline
Today it means: A strap used to carry objects tied to its ends by placing the broadened or cushioned middle of the strap over the head just above the forehead. Full definition →