Tradition history seeks to analyze biblical literature in terms of the process by which biblical traditions passed from stage to stage into their final form, especially how they passed from oral tradition to written form.
Tradition history/criticism is a sister discipline of form criticism—also associated with Gunkel, who used the results of source and form criticism to develop the history of tradition interpretation.
Tradition history forces interpreters to consider the possibility that some texts may have had an oral prehistory.
It also notes that past traditions were retold and used for a present purpose; that it was made real, vital, or relevant for each successive generation.
If texts were written soon after they were spoken so that there was not a long oral prehistory, then the assumptions of tradition history fall to the ground.