Complex sentence: The human population of Shiqu County was approximately 63 "400 and 96.8% were ethnic Tibetans; there were 49" 100 herdsmen, representing 77.6% of the population.
Split into simpler sentences: The human population of Shiqu County was approximately 63,400,96.8% of which were ethnic Tibetans. There were 49,100 herdsmen, representing 77.6% of the population.