There are a number of resources available on people groups. However, not every obscure people will have much written about it. Here are a few suggestions:
EBSCO Quick Search: a multidisciplinary database search in our library
The Joshua Project: an online database of unreached people groups
Operation World: an online website with people group information arranged by country
The Ethnologue: an online site tracing the development of culture and language
If you have any additional questions, feel free to reach out to us at (434) 592-3362 or at firstname.lastname@example.org.