ðə ɹˈɪtsɚɹɪˌoʊ kˈoʊdz wɜː mˈɑːdəld ˈæftɚ ðə sˈɪvəl ænd pˈiːnəl kˈoʊdz ʌvðə tˈæŋ dˈaɪnɐsti, ɪn pɚtˈɪkjʊlɚ, ðə kˈoʊd ʌvðɪ ˈiəɹə pˈæst ɪn sˈɪkshˈʌndɹɪd fˈɪfti wˈʌn wˌɪtʃ wʌz ðˈɛn kˈɜːɹənt ɪz nˈeɪmd baɪ skˈɑːlɚz æz ðə bˈeɪsɪs ʌvðə tˈuː ɹˈɪtsɚɹɪˌoʊ kˈoʊdz.
The ritsuryō codes were modeled after the civil and penal codes of the Tang dynasty, in particular, the code of the  era passed in 651 which was then current is named by scholars as the basis of the two ritsuryō codes.