although the concept may also refer to other tripartite divisions of historic time-periods. In history, archaeology and physical anthropology, the three-age system is a methodological concept adopted during the 19th century according to which artefacts and events of late prehistory and early history could be broadly ordered into a recognizable chronology. C. J. Thomsen (1788-1865), director of the Royal Museum of Nordic Antiquities in Copenhagen (in office: 1825-1865), initially developed this categorization in the period 1816 to 1825 as a result of classifying the museum's collections chronologically - there resulted broad sequences with artefacts made successively of stone, bronze, and iron.