Prison in the past wasn't very long term without any slavery - with agricultural scale having people not doing any work wasn't affordable. Hold until the judge gets there or they decide what to do with them unless they are say nobility elite wealthy or otherwise able to justify the expense (ransom or a hostage).
Egypt would be in a good situation for that given seasonality and nile flooding giving better yields.
> The Bible records Joseph as being put in prison in Egypt c.1500 BCE.
Newer evidence strongly suggests the exodus took place during Egypt’s Middle Kingdom (c. 1450), dating Joseph’s deportation and rise to power at roughly 1900 BCE.
Egypt would be in a good situation for that given seasonality and nile flooding giving better yields.