Explain why archaeology is a cooperation of many sciences?

Historical archaeology is the concurrent study of material culture and documentary evidence. The practice of historical archaeology is rooted in the study of the European settlement of North America and, in particular, of the early seventeenth century colonial settlement in New England and the Chesapeake. More recently, this emphasis on the settler and colonist has been balanced by the emergence of an archaeology of slavery, and by the development of a variety of specialized subfields. Furthermore, the overwhelming association between historical archaeology and North America has been challenged by strong developments in other parts of the world. Each regional focus has tended to develop its own identity while remaining linked to the core concepts of this discipline. Despite these developments, though, historical archaeology still remains overwhelmingly the archaeology of European colonial expansion. The archaeology of colonial contact—and the impact of European colonial expansion on the other side of colonial frontiers—remains largely unexplored. And the historical archaeologies of other large-scale, literate systems such as those of China or of Islamic expansion and settlement remain outside the scope of the field.

where are the statements?