We are likely to forget that civilization in Malaya extends further back than the founding of Rome, so when we ascribe the origin of this phrase to the Malays we must bear in mind that it is not an indiscriminate custom of the people, just isolated practice.
The Malay word amoq means “frenzied,” or, with extended implication, “engaging furiously in battle.” Various causes may exist, but there seems to be an underlying temperament among Malayans that makes them peculiarly susceptible to fits of depression.
Such a spell may be caused by jealousy, or by despair, and it may be aggravated by excessive recourse to opium or other drug. Its effect is to seize the victim with a murderous frenzy.
He snatches a cutlas, or native kris, and dashes out into the road striking at any and everyone he meets. A cry of “Amoq! Amoq!” goes up among the people, and perhaps before the madman has been able to do much damage he is himself killed.
English use of the phrase has become more figurative than literal; we may say that a person has “run amuck” when we mean no more than that he is engaging in an unreasonable attack upon the established social order.