T code and any other way to upload sales history & inventory into planning table SOP SAP ECC

Hi Team,

I am new in Sales & operation planning. Actually client want to load sales history and inventory levels by plant/SKU & country each week into planning table into SAP ECC using external file excel or text in S&OP. Please suggest is there any tcode & any other way to do the same.

Please suggest.

Thanks,

Sachin