The Chinese character ⟨東⟩, writing a word meaning ‘east’, is shown here to have arisen in connection with the use of the vertical gnomon in the determination of cardinal direction. The simple geometric procedure involved—by Al-Bīrūnī termed the “Indian Circle”—is attested across a number of other early cultural contexts, and has a Chinese history traceable from classical-era technical treatises such as the “Kǎogōng jì” 考工記 to sixth-century commentary to the mathematical text Shùshù jìyí 數術記遺. Evidence offered below constitutes the first (...) direct indication for such a practice in second-millennium BCE China. (shrink)