TITLE: Did the notion of "angle" originate with Thales?
QUESTION [14 upvotes]: Thales (circa 600BC—roughly 50 years before Pythagoras, 200 years before Plato,
and 300 years before Euclid)
certainly knew and reasoned with the concept of a planar angle.
Are there earlier historical references to angles in
a mathematical sense?
Or is the origin of the notion lost in the mists of antiquity?

REPLY [5 votes]: The division of a circle into 360 degrees may well have originated from ancient Babylonian mathematics (1800 BC), as evidenced by a clay tablet from Shush. Here is a quote from David Wallis, History of angle measurement:

See also A History of Pi (pages 21-22).