The Americas in the medieval world (500 – 1500). A thousand years of kingdoms, caliphates, steppe empires and trading cities between the fall of Rome and the voyages that joined the hemispheres.
Maya astronomers put Venus's cycle at 584 days, near NASA's 583.92, and the year at 365.242 days, using sighting sticks. A Venus table survives in Dresden.
· AD 900Southern Maya cities stopped dating monuments by AD 998. Lake cores, a stalagmite, Aguateca's walls and lidar each explain part of why they emptied.
· AD 900A 2023 PLOS ONE model of 102 radiocarbon dates puts Tiwanaku's monument building at AD 590 to 720 and its collapse at 1010 to 1050, before a drought.
· 1010Ancestral Pueblo people carried about 240,000 beams 75 km into Chaco Canyon from 850 to 1130, then moved on in a drought; 19 Pueblos and the Hopi claim it.
· 1050Monks Mound, 291 by 236 meters at one contour, anchored Cahokia in Illinois, a city of about 120 mounds and nearly 20,000 people about 1100, empty by 1350.
· 1100On December 18, 1888, two ranchers looking for cattle saw Cliff Palace. Eight collections, a Swedish dig and the Antiquities Act of June 8, 1906 followed.
· 1250About AD 1200 Moundville, Alabama, was a palisaded town around a mound-lined plaza. After 1300 most residents left and it became a burial center.
· 1250Peru's Ministry of Culture called Chan Chan a masterpiece of pre-Columbian design in 2016, the year Huaca Toledo was excavated and rain closed the site.
· 1300A 2021 Antiquity study dated Machu Picchu's occupation to about 1420, before Pachacuti's 1438 accession. Yale returned its collection to Peru by 2012.
· 1450
