Complex sentence: Lane's account was quite accurate in terms of his description of the town, its location and structures, but the population estimates may have accurately been between his (which might have been 4,000 for all the people, and Harriot's, about 2100 overall).
Split into simpler sentences: Lane's account was quite accurate in terms of his description of the town, its location and structures. The population estimates may have accurately been between his (which might have been 4,000 for all the people, and Harriot's, about 2100 overall).