A yojana (Devanagari: योजन; Khmer language: យោជន៍;[1] Thai: โยชน์; Burmese: ယူဇနာ) is a measure of distance that was used in ancient India, Cambodia, Thailand and Myanmar.
Various textual sources from ancient India define Yojana as ranging from 3.5 to 15 km.
[2][3] Ashoka, in his Major Rock Edict No.13, gives a distance of 600 yojanas between the Maurya empire, and "where the Yona king named Antiyoga (is ruling)", identified as King Antiochus II Theos, whose capital was Babylon.
A range of estimates, for the length of a yojana, based on the ~2,000 km from Baghdad to Kandahar, on the eastern border of the empire, to the ~4,000 km to the Capital at Patna, have been offered by historians.
In Hindu scriptures, Paramāṇu is the fundamental particle and smallest unit of length.