Katyayana , Likhita , Manu [1] , Parasara , Samvarta , Shankha , Shatatapa , Ushanasa , Vashishta , Vishnu , Vyasa , Yajnavalkya and Yama . These twenty-one rishis were the propounders of Smritis . The oldest among these smritis are Apastamba, Baudhayana, Gautama, and Vasishta Sutras . Nature of