When importing through Excel, what is the minimum number of columns to allow an import to work?

After exporting a Shared Content to an Excel sheet, I would like to update only the data I am touching, so I tired to delete the columns of data that were not relevant to prevent accidentally overwriting changes that might have happened since exporting.

However when I try to import it doesn't import any of my new data.

What is the minimum amount of column headers required to get your excel import to update a shared content list via data? Does it need to have every column defined for the system to accept the updates?

I am looking to mitigate the risk involved in updating a lot of data through the excel import feature.