Complex sentence: Emerging from that vacuum was Teotihuacan, first settled in 300 BC. By AD 150, Teotihuacan had risen to become the first true metropolis of what is now called North America.
Split into simpler sentences: Emerging from that vacuum was Teotihuacan, first settled in 300 BCE. By 150 CE, Teotihuacan had risen to become the first true metropolis of what is now called North America.