Deep Time · Side by side

Two chapters, the same questions asked of both

Put two Deep Time chapters next to each other — their evidence base, the dating methods behind them, the live debates, and the questions still open.

Documented1300 – 1521 CE

Aztec

Lake-city agriculture, tribute economics, and codices written on both sides of conquest.

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Documented1438 – 1533 CE

Inca

Road systems, khipu record-keeping, and stonework still being reverse-engineered.

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The evidence base

Excavations in and beneath Mexico City, indigenous and colonial-era codices, Nahuatl-language texts, and Spanish accounts written by participants and their descendants.

Monumental stone architecture, the road network, khipu cord records, Spanish administrative inspections, and Andean archaeology across a vast altitudinal range.

How we know
MethodWhat it constrains
Urban excavationTemplo Mayor precinct and offering depositsDirectly tests textual descriptions of ritual. Much of the city remains under a modern capital.
Codex analysisPictorial manuscripts and Nahuatl alphabetic textsPreserves indigenous accounts; most surviving copies were produced under colonial conditions.
BioarchaeologySkeletal remains from ritual and burial contextsEstablishes practice and demography without confirming reported totals.
MethodWhat it constrains
Architectural and quarry analysisTool marks, unfinished blocks and abandoned quarry stonesDocuments shaping and transport methods. Exact logistics of the largest blocks are still modelled.
Khipu structural studyCord, knot type, ply direction and colour in surviving khipuNumerical content is readable. Whether narrative content is encoded remains open.
Colonial administrative recordsInspections and tribute assessmentsPreserves detail about the Inca system through a Spanish administrative lens.
Where specialists disagree
  • What was the scale of human sacrifice?

    Skull-rack excavation confirms the practice; Spanish-reported totals remain contested.

  • How coercive was the tribute empire?

    Provincial evidence shows a spectrum from garrisoned control to negotiated tribute.

  • Do khipu encode language as well as numbers?

    Some khipu resist purely numerical interpretation; no reading has been independently reproduced.

  • What was Machu Picchu for?

    Royal estate is the leading reading, based on a colonial land document and site layout.

Still open
  • How much of Tenochtitlan is recoverable beneath Mexico City?
  • How did the lake hydraulic system function in detail?
  • What did pre-contact population figures actually look like?
  • Can khipu be read beyond accounting?
  • How were labour obligations organised across the whole empire?
  • How much high-altitude archaeology remains unsurveyed?