Tribal cultures.
As great as an aid technology is in recording cultures of small tribes, before they are assimilated by The Rest of Us, it is still a losing race against time for anthropologists.
There simply are not enough funds and people to do the job.
Adding to the difficulty is the necessity to engage in a multi-year documentation, preferably by the same team. Since there may be tribal practices that only happens every few years, or to document how a tribe responds to environmental stress, or simply to document the impact of 'modern' society.
What a loss.
