Letters to the pope in new book

One letter from 1200th century where Djingis Khans grandson demands that the pope will give in for the mongols is showed in the new book ”The Vatican Secret Archives”. Among the letters is also a letter from 1550, where Michelangleo reminds the pope that he still awaits payment for one of his paintings. Another document is from 1863 where Jefferson Davis (President of the south states in the american civil war) says that the ongoing war in USA is because ”the agression of the northern states”. Of 105 letters in the book 19 has never been shown before.