King Solomon's Mines tells of a search of an unexplored region of Africa by a group of adventurers led by Allan Quatermain for the missing brother of one of the party. It is the first English adventure novel set in Africa, and is considered to be the genesis of the Lost World literary genre. The book was first published in September 1885 amid considerable fanfare, with billboards and posters around London announcing "The Most Amazing Book Ever Written". It became an immediate best seller. By the late 19th century, explorers were uncovering ancient civilisations around the world, such as Egypt's Valley of the Kings, and the empire of Assyria. Inner Africa remained largely unexplored and King Solomon's Mines, the first novel of African adventure published in English, captured the public's imagination.