Stream now with KPBS Passport / Watch Wednesday, Sept. 3, 2025 at 10 p.m. on KPBS TV + Sunday, Sept. 7 at 10 p.m. on KPBS 2. Recent discoveries and technological advances shed new light on our understanding of pre-Columbian societies in the Amazon. Scientists speculate the rainforest was home to between 8 and 10 million people living in large, well-established communities.