Indian cricket team recently thrashed South Africa in test series and claimed the trophy with 3-0 margin. This is first occasion when India beat South Africa in all test matches of the series. Eventually this is not the first occasion when Indian team won all matches of the test series.
First occasion came in 1992-93 when India beat England in home series by 3-0. After that team India defeated Sri Lanka in all three matches and did clean sweep. England, Sri Lanka, Australia, New Zealand and South Africa are the countries against them India won all tests in the bilateral series.
India Winning All Tests in a Series