S.D. Codified Laws § 7-19-9

In all cases where real property has, prior to July 1, 1935, been conveyed by deed to any county in satisfaction of a mortgage on said land securing the payment of a state permanent school fund loan and such real property has been thereafter conveyed by such county, no action or proceeding to invalidate, set aside, or annul such conveyance by the county on the ground of any alleged defect in the proceeding for the acquisition of such real property by such county or in the proceedings for the subsequent conveyance of such property by the county shall be maintained, any existing statute to the contrary notwithstanding.