Final answer:
Our knowledge of the Indus Valley civilization is based solely on archaeological findings, such as urban infrastructure and artifacts, as their script remains undeciphered, leaving a gap in understanding their written history, laws, and literature.
Step-by-step explanation:
Everything we know about the Indus Valley civilization comes from archaeology because there are no decipherable written records left by this ancient civilization. The inability to read the Indus script means we lack direct insights into their sociopolitical structure, religious beliefs, and daily life practices that written documents typically provide.
Instead, we rely on archaeological evidence such as urban planning remains, drainage systems, bricks, artifacts, and the layout of cities like Harappa and Mohenjo-Daro to infer the civilization's culture and organization.
Without written documents, elements such as philosophy, laws, literature, and historical events become difficult to understand. Archaeological analysis of artifacts, buildings, and urban layouts offer vital clues, yet they can only provide a partial picture of the Indus Valley civilization's complex history.
The meticulous urban planning, advanced technology, and spiritual life apparent in the artefacts excavated from sites like Dholavira, Harappa, and Mohenjo-Daro suggest a sophisticated and organized society whose full complexity remains locked within an undeciphered script.