Sorting ONLY a certain area, possible?

I see no way to specify a particular area (which columns, by which rows -- which specific cells) to include in a sort?

I have data lying in rows beneath the data which I will sort [many times], but don't want that lower data to get messed up or reordered by the sort.

Is there a way to do this? In Filter & Sort - Custom Sort, there are no rows by columns options that you can set, so I'm wondering if you can specify the cells to sort any other way?

Thanks so much!!