Modeled on 《孟子·梁惠王上》: 不远千里而来 - where King Hui of Liang praises Mencius for crossing a thousand li to advise him. Later usage intensified 千里 to 万里 ('ten thousand li').
grammar
The literal reading is '[subject] does not consider ten thousand li far.' Always followed by a purpose verb: 不远万里 + 来/去/赶来 + reason. Emphasizes commitment, not just distance.
