> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/faq/help-topics/no-data/historical-backfill-returns-nothing/polar-no-pre-auth-history-and-manual-excluded.md).

# Why does Polar return no historical data?

Polar's API does not allow retrieving data recorded **before the user authenticated**, and historical retrieval is limited to roughly 30 days back from the connection date. Requests for dates prior to connection return an empty array, which is expected, not an error.

In addition, sessions entered manually through Polar's web diary are not exposed by Polar's API. Only sessions recorded or synced through Polar devices/apps that reach the Polar API come through.

These are provider-imposed limitations, not Terra configuration issues.