Old English tange, tang "tongs," from Proto-Germanic *tango (cf. Old Saxon tanga, Old Norse töng, Swedish tång, Old Frisian tange, Middle Dutch tanghe, Dutch tang, Old High German zanga, German Zange), literally "that which bites," from PIE root *dank- "bite" (cf. Sanskrit dasati "biter;" Greek daknein "to bite," dax "biting"). For sense evolution, cf. French mordache "tongs," from mordre "to bite."
"Chinese secret society," 1883, from Cantonese t'ong "assembly hall."