sumifs-exclude values from criteria columns

[shriguru]

I need to add values in cells of column "B" if the date in respective cell in column "c" is newer or older to certain date.
e.g Add all values in cells of column B if the date in respective cells in column C is older to 01-01-2020.
Isuue is in certain cells of column "C" there are non date entries like numbers and result of formula .I want to exclude those entries. I want the values in cells of column "B" to get added if the respective value in cells of Column C is a date.

Thanks

 

[arthurbr]

Are your dates real dates or text looking like dates ? ( text=left aligned in cells if no manual alignment applied)

 

[shriguru]

text looking like dates