What processes are used to reconstruct history when written history is missing or limited?
answer with at least 2 full sentences

Historians and archaeologists have three methods to reconstruct history: through primary sources, secondary sources and the oral history. Primary sources include the artifacts, videos and letters; while secondary sources are through books and reports. Oral history, on the other hand, are not written sources. They are passed on to generations through stories, songs, and may manifest in their customs and traditions.