Per 《
新华词典》:
又称武当拳,
相传源于宋代,
为武当道士所传 — 'Also called Wudang Boxing; traditionally said to originate in the Song dynasty, transmitted by Wudang Taoist priests'. Paired with
外家拳 (external arts, Shaolin-derived). Founders are legendary (Zhang Sanfeng for some lineages).