These repositories specialize in data created by anthropologists or archaeologists, and are very useful places to find data sets that you can use. This data may be numerical, or it may be in other forms: maps, photographs, interviews, etc. Some have curated subject headings and other standardized metadata, and some rely on natural language keyword searching.
It is useful to read the 'about' pages for each site before you begin, and also to review the help notes, to understand the best way to find useful data within these databases. Be brave, click through to view the data attached to the reports or textual components and assess the data itself, and what you can do with it (it it downloadable, in what formats, etc?).