First, we know that new archaeological investigations into the civilization have provided new evidence; however, we do not know whether these were the most recent archaeological investigations into the civilization.
Second, we are provided with no information about the field of archaeology as a whole. We know that, for this particular civilization, there exists limited written evidence; however, this does not support concluding that the author believes that there is a trend in the field to avoid over-relying on written evidence.
Hope this helps! Please let us know if you have any further questions.