Sentence:  All this emphasis on Centrality and on the number 5 as a symbolic expression of the Center , which seems to have <WSD>begun</WSD> as far back as 400 B. C. , also may conceivably have led to the development of the Five-Elements School and the subsequent efforts to fit everything into numerical categories of five . 
Meaning of the word marked with <WSD> tags:  have a beginning, in a temporal, spatial, or evaluative sense