The earliest historical record of the Sultans of Brunei is not clearly known due to the poor early documentation of Brunei history. Many elder members of the House of Bolkiah claim that their ancestors were the BaHassan and BaAlawi Saadah from Tarim and Hadhramawt in Yemen. In addition there has been an effort to Islamise the history, with the "official history" not matching up with verifiable foreign sources. The Batu Tarsilah, the genealogical record of the kings of Brunei, was not started until 1807. Therefore, much of the intepretation on history relied on earlier Chinese sources and legends. It seems that the early Sultanate of Brunei was dependent on Chinese support, and perhaps early Sultans were of Chinese origin. Furthermore the earliest Sultans may have been practising the Hindu or Buddhist religions, with early names indicating this origin.