əpˌɑːn ðə dˈɛθ ʌv hɪz dᵻsˈɛndənt dˈuːk bˈɑːlslɔː ɹˌoʊmən θɹˈiː ɹˈaɪməθ ɪn wˈʌn θˈaʊzənd wˈʌnhˈʌndɹɪd θˈɜːɾi ˈeɪt, ɪt wʌz ˈæləkˌeɪɾᵻd tə ðə nˈuːli ɪstˈæblɪʃt dˈʌtʃi ʌv mæsˈoʊviə, ɐ pɹəvˈɪnʃəl dˈʌtʃi ʌv pˈoʊlənd.
Upon the death of his descendant Duke Bolesław III Wrymouth in 1138, it was allocated to the newly established Duchy of Masovia, a provincial duchy of Poland.