Thanks.
http://en.wikipedia.org/wiki/Prosopography
In historical studies, prosopography is an investigation of the common characteristics of a historical group, whose individual biographies may be largely untraceable, by means of a collective study of their lives, in multiple career-line analysis.[1] Prosopographical research has the goal of learning about patterns of relationships and activities through the study of collective biography; it collects and analyses statistically relevant quantities of biographical data about a well-defined group of individuals. This makes it a valuable technique for studying many pre-modern societies. Prosopography is an increasingly important approach within historical research.